Okay, got around to trying to today. Few things that come to mind that haven't been covered by others a bunch, or in as much detail at least.
1. First, skimming the ground. In Firefall, what I consider a VERY important part of being able to smoothly fly around and be mobile in areas, especially some of the slightly hilly/duny areas near the beaches, was the ability to simply skim across the ground with your jets on. If you are flying forward, and hit the ground, or you were losing altitude, started your jets and bump into the ground (as l long as it's not too hard) if you are still holding space, and still had energy, you'd keep your jets on and just start skimming over the ground keeping your rough momentum.
In the Em8er movement demo, with all its little dunes, if you fly towards one and bump into it, or the ground, even just lightly, you'll stop flying even if you still have energy and are holding space. This breaks your movement and flow. If you could super fast kick off and jump into the air and jet again with almost no lag it'd not be so bad, but right now it feels very clunky dropping into ground mode suddenly, and with its laggy moment and slow response to start jetting again.
2. Second, changing directions while jetting tends to make you fly upwards. If you run forward, jump and jet, you go forward mostly, up a bit, try to turn and almost all of the thrust goes into upwards thrust after the omniframe stops its current horizontal movement. Right now if you want to change direction, you pretty much have to let go of the jet key so you start falling a bit, and then hit it again while holding in the new direction you want, do this a couple times to try and "break" the previous inertia" and then start a given jump in the direction you want, even if just a little in that direction. Only if you started a jump in a given direction does is seem to let you move horizontally in that direction, all others mostly give you upwards thrust. Using sprint directional jetting you could quickly change directions in the air, but without gaining altitude. Some extra control for the player.
I feel that it might be a good idea to just split up the mostly upwards versus the horizontal movement into two categories. Jet sprinting, and normal jetting. Normal jetting is just space bar and has a lot of upwards movement applied, with some directional if also input. Shift/sprint plut space/jet input though could focus almost entirely on horizontal speed.
This could go nicely with ground skimming, since if you can smoothly slide over surfaces somewhat, then it could be a good way to get around more quickly at ground level, that is faster than normal sprint, but does cost energy to use.
Direction changes overall felt very slow, especially in the air, but also somewhat on the ground. When you try to stop moving, you take awhile to stop, or if you turn quickly you suddenly break your speed and slowly start up again. The animations also made it feel to "flowy" like it's just moving with the inertia and gradually turning. I recall you not wanting pacific rim style heavy mechs, but more fast and mobile ones like gundam, but I feel aiming for a bit of a mix is a good idea. By mix I mean relatively fast responsiveness (like gundams, so gameplay is fast), but to let units feel heavy in animations like with pacific rim style. The idea being a mech can change directions while running suddenly to the side, rather than slowly, but visually it does so with very forceful steps, like yes it has a LOT of weight behind it, but your suit is super strong and can plant one foot down and immediately throw itself in the other direction if needed, rather than needing to slow down and change direction over a couple steps or so.
Similarly landing from high altitude could have a nice drop with the waist, like if you slam into the ground, make you SLAM into the ground, with it showing weight, but the suit still absorbing it and moving into its next action, just with a lower pelvis and torso angle blended in for a short bit to the animations.
I understand this is largley stuff to work on later, animations and all, but having it in mind for the movement now, and then for the animations later could help it all come together nicely if yo decide to go in this direction.
Right now, the feeling is a bit more pacific rim realistic style, given that while not super huge, we are only in the ten or so feet tall category, rather than unrealistic or overpoweringly agile movements like you might find in some animes or such.
3. And while fairly minor, some other animation parts like having the wings start to shake or vibrate a bit as you freefall more quickly might help. In general, little things that help your movement feel fast, and like there's more energy involved can improve the feeling of awesomeness and bad assery as you charge around in your kick ass power suit doing insane stuff.
4. Keybinds list int he options or something, even if not able to be set, it'd be nice to have all keys visible. I found crouch on alt, but figured it'd be on ctrl. Also didn't find a key for rotating the camera but not my mech (wanted to look at it from the front during some motions, or even just standing).