Ok, so here's what I have.
On my player, I'm only using simplemove and Character Controller to move around. There's no rigidbody at all.
When the player picks up a glider, I send an event to the move FSM which is still using Simple move to move the player around, the only difference is that now I'm using Get Property from Character Controller to find out if the player is on the ground or not. As soon as they jump or leave the ground, I send a transition.
In this "gliding" state, I'm again doing something similar with Simple Move, but I've tried setting the Y velocity to a positive and negative number in an attempt to slow the fall. So far as I can tell, it does nothing at all. I know that in the screenshot every frame isn't checked, but I've tried that already.
Is there another property that I should be using? Or maybe a different character "motor" like you mentioned earlier?