Might have (definitely) been mentioned, before, somewhere. Somewhere-shire. But, I just wanted to create another breakdown of how mobility would work with the three frame-types and any builds/tweaks between them.
Nothing complicated or too unreasonable, really.
Obviously, in terms of speed (movement>running>sprinting, skimming and flying) the Sly-Dancer should be considerably faster than the other two. Maybe starting from as high a difference as, say, 1.5x that of the medium and heavy frames. Which could be further upgraded (built) to be even 2.0x that, max. Their thrusters (specifically the two burners over and above on both sides of the head) should enable it to manuever faster, finer and longer, in the air than the other frames. They could have a specific backwards, forwards and sideways dash ability that would be different from simply firing their jetpacks while pulling in one direction. Imagine the typical dash move from third-person or even side-scrolling action-platformers. Like, Mega Man X. Now, translate that onto a 3d plain and you could shoot not only forwards, but backwards and sideways, while facing (and shooting) forwards. So, you don't actually turn around in the direction you're dodging and you can essentially back-pedal while shooting at a target, even. This isn't anything new. I recall some Japenese mecha-games having maneuvering like that (e.g.: Nier Automata).
What could present more work, would be designing an energy-allocation/regulation system, located in the chassis (that would, of course, be a modifiable part), which would allow for fine-tuning for how the thrusters would work. And this is something I have, indeed, mentioned, already. Every frame, not just exclusively lighter ones, could choose to either have quick bursts of thrusts or continues burns for these types of manuevers. Depending on the weight-class, these thrust could use differing amounts of energy. But even those builds that would just dash, skip, slide, glide, jump, leap...etc., in quick burst couldn't do it forever. They, too, would have to pay attention and not accidentally deplete their ever-recharging reserves. Same as if they had been using longer, sustained burns to jet around. For balance's sake. Some games actually give dash-charges, like 2 to 5, that if used in quick succession, one would have to wait for, at least, one charge to be available, before they could dash/dodge, again.
Heavy frames, with their strong, heavily energy-consuming back-thrusters could have a ground-slam move (not an ability that would take up a slot and maybe not even a move that need to be unlocked, but a basic thing) that they could effectively use from the height of 3-4 frames to pound the ground. It could stun smaller enemies, when impacting within close to (or in) melee-range to them. When hitting them, it could do considerable damage and could still apply a stun-effect, on top of it, pun intended. When hitting larger enemies, it could either momentarily slow them in their advance (not necessarily stun), just making it take the next (couple) of steps much slower. Some larger foes could shrug it off. Others could be stunned. But, this could potentially lead to a stun-lock exploit, which could either break the game or encourage team coordination. Heavier frames could kite behemoths and keep rattling them, slowing them, stunning them, while others could shoot and melee from different angles. While one heavy would slam into the enemy and wait for his energy to recharge, another heavy frame could slam into the enemy, to keep them back, alternating and timing their attacks, while giving one another time to recharge and manage their energy reserves.
Medium and light frames wouldn't have this move.
With all that said, a lighter frame could eventually be tweaked and equipped with such gear that it would weigh it down so it would be as slow as the slowest possible medium frame build, but with stronger weapons, for example. Or a few more bits of armor.
The same way, a medium-frame could be upgraded to be either as fast as the slowest light-frame or be as slow as the fastest heavy-frame, depending on the weapons, body-parts...etc. the player would put in, with trade-offs in mind.
And, of course, a heavy-frame, through a specific build, could be as fast as the slowest medium-frame.
So none of their speeds could ever really overlap. Increase or decrease, it would still keep their mobility limited/unique to their frame's weight-class.
It would be dumb if a heavy-frame had servos that would make their legs move like Michael Flatley on crack. I always found that ridiculous in Firefall, when I saw some big, bulky bastard run with such a fast limb-animation (that was also a class-specific ability of theirs, I think...some crack speed-boost...but, it doesn't/wouldn't/shouldn't suit such heavy classes).
So, yeah.
Nothing complicated or too unreasonable, really.
Obviously, in terms of speed (movement>running>sprinting, skimming and flying) the Sly-Dancer should be considerably faster than the other two. Maybe starting from as high a difference as, say, 1.5x that of the medium and heavy frames. Which could be further upgraded (built) to be even 2.0x that, max. Their thrusters (specifically the two burners over and above on both sides of the head) should enable it to manuever faster, finer and longer, in the air than the other frames. They could have a specific backwards, forwards and sideways dash ability that would be different from simply firing their jetpacks while pulling in one direction. Imagine the typical dash move from third-person or even side-scrolling action-platformers. Like, Mega Man X. Now, translate that onto a 3d plain and you could shoot not only forwards, but backwards and sideways, while facing (and shooting) forwards. So, you don't actually turn around in the direction you're dodging and you can essentially back-pedal while shooting at a target, even. This isn't anything new. I recall some Japenese mecha-games having maneuvering like that (e.g.: Nier Automata).
What could present more work, would be designing an energy-allocation/regulation system, located in the chassis (that would, of course, be a modifiable part), which would allow for fine-tuning for how the thrusters would work. And this is something I have, indeed, mentioned, already. Every frame, not just exclusively lighter ones, could choose to either have quick bursts of thrusts or continues burns for these types of manuevers. Depending on the weight-class, these thrust could use differing amounts of energy. But even those builds that would just dash, skip, slide, glide, jump, leap...etc., in quick burst couldn't do it forever. They, too, would have to pay attention and not accidentally deplete their ever-recharging reserves. Same as if they had been using longer, sustained burns to jet around. For balance's sake. Some games actually give dash-charges, like 2 to 5, that if used in quick succession, one would have to wait for, at least, one charge to be available, before they could dash/dodge, again.
Heavy frames, with their strong, heavily energy-consuming back-thrusters could have a ground-slam move (not an ability that would take up a slot and maybe not even a move that need to be unlocked, but a basic thing) that they could effectively use from the height of 3-4 frames to pound the ground. It could stun smaller enemies, when impacting within close to (or in) melee-range to them. When hitting them, it could do considerable damage and could still apply a stun-effect, on top of it, pun intended. When hitting larger enemies, it could either momentarily slow them in their advance (not necessarily stun), just making it take the next (couple) of steps much slower. Some larger foes could shrug it off. Others could be stunned. But, this could potentially lead to a stun-lock exploit, which could either break the game or encourage team coordination. Heavier frames could kite behemoths and keep rattling them, slowing them, stunning them, while others could shoot and melee from different angles. While one heavy would slam into the enemy and wait for his energy to recharge, another heavy frame could slam into the enemy, to keep them back, alternating and timing their attacks, while giving one another time to recharge and manage their energy reserves.
Medium and light frames wouldn't have this move.
With all that said, a lighter frame could eventually be tweaked and equipped with such gear that it would weigh it down so it would be as slow as the slowest possible medium frame build, but with stronger weapons, for example. Or a few more bits of armor.
The same way, a medium-frame could be upgraded to be either as fast as the slowest light-frame or be as slow as the fastest heavy-frame, depending on the weapons, body-parts...etc. the player would put in, with trade-offs in mind.
And, of course, a heavy-frame, through a specific build, could be as fast as the slowest medium-frame.
So none of their speeds could ever really overlap. Increase or decrease, it would still keep their mobility limited/unique to their frame's weight-class.
It would be dumb if a heavy-frame had servos that would make their legs move like Michael Flatley on crack. I always found that ridiculous in Firefall, when I saw some big, bulky bastard run with such a fast limb-animation (that was also a class-specific ability of theirs, I think...some crack speed-boost...but, it doesn't/wouldn't/shouldn't suit such heavy classes).
So, yeah.