Ah I see now...
I am curious how "slowing down" will work as it looks like with the subjective gravity for those who can't fly ... you can't really. The PCs just crash into something going 150/300 feet each round. I would guess the only way to safely slow down would be to time the gravity change right as a PC is near something solid and "fall" onto it at a right angle as to minimize fall damage. i.e. fall past solid surface and then as they are move the surface change the direction of "down" onto the surface and then just fall a few feet onto that surface.
Going to be interesting and tricky to run well, but now that I can picture it I think I have a plan of attack.