How come (when in flying mode) STK2 can descend slowly (while pressing W, A & D at the same time) but STKM can't?
It might be the order in which the keys get pressed; you really only need to press a and d (or left and right for stkm) to do that.
EDIT: I'm thinking of rocket boots, my bad.
Pressing up for STK2 allows it to descend at a much slower rate than just holding left and right, but for STKM does not work.