i realize it prevents cheesing all the puzzles, but it feels odd to not have the ability to control yourself midair after a gravity flip. another thing that feels weird: jumping with up!
in terms of control assignments, controller support is always nice (especially for people who find keyboard controls painful) in terms of the loss of control: it would be best to find a way to make the puzzles immune to the cheese, but another approach might be to always remove the ability to control your trajectory after jumping (and apply some scaling factor to the horizontal velocity so that a single jump will never reach all the way across)