Yoo, ground-type gameplay! I'm always surprised people seem to like the walking/running a whole lot. Guess Bungie really did hit gold with the vehicle controls in Halo. The lower energy costs definitely feel nice as well.
I've definitely also been hearing a lot of feedback on the enemy missile spam. Probably going to rework some enemies so there's a bigger interval between firing during streams of missiles. That way, you have more time to get out of the way or into cover instead of eating the entire stream in half a second. Alternately, have them fire the missiles in a shotgun-pattern so it's harder to dodge but only half the missiles will ever hit the player.
As for the Ground Burst delay, it probably has something to do with your mech being underweight. At lower weights, you get more speed than usual from your boosters so braking takes a bit longer. Combine that with your Impulse III boosters and boy howdy.
That aside, glad you're enjoying it!