This is a very fun idea! I think you did a good job making the float mechanic feel solid to use. I would say that I did feel like I could cheese it a bit, by just switching back and forth as much as I wanted.
It could be nice to add a cooldown on the switch and expand the level size a bit. This way you have a more freefall feeling and you have to really time it and use your gravity well. Overall good work though!