Ya, you got to mix and match it all with more variables than just power, and design each part with it's own basic limits.
Weight applies to everything from armor type, gun size/weight, all of that stuff. Accuracy recoil can also be affected by speed and frame weight limits, cram too many abilities or an oversized reactor onto a light frame and it might not be that fast anymore.
Also boosting ability recharges is nice, but they should probably have maximum charge speeds before they'd just burn out, so if you have a power shunt sending 90% of power to recharge abilities, no you can't just socket one ability and expect it to recharge virtually instantly since it'd get all that power. If a player wants only two abilities that recharge faster over say three that gives them more flexibility or options then okay, but keep it within reason by basic limits on each item. And not the annoying exponential curve of falloffs type, people feel inclined to game those to still push the limit that little bit, this tends to be less fun than just having a basic reasonable wall in place when building, and also makes balance a lot harder to manage.
Also while the heavy frame might have all the strength in the world, that doesn't mean it could stop on a dime if it loads up on tons of everything. Besides still having a hard cap it will still end up being relatively slow, while also being a larger easier to hit target that can't fly or get around as well making it harder to engage others. A light frame could normally fly up to a kaiju and shoot it's spine easily, a heavy frame might only just manage by default. Load it up a ton and sure you might have an impressive gun with a lot of damage but you just won't be able to overcome all the extra weight within the limits of the jets meaning you can't fight those types of enemies very well. Now if you are just standing at a base with a clear field of vision at enemies charging at you through a valley you may do awesome with that frame. So in this case you can specialize a lot, be good and flexible, but in the end you always still have caps to keep you within reason (that super heavy one still doesn't deal more dmg than a lighter heavy frame with the same gun, it just has the gun AND the armor in it's case).