Regarding timings to create interesting dynamics, I think this could work as a more real time / action based game but because the mechanic is so unique, it's difficult to intuitively control. Perhaps some sort of slowdown effect for 1-2 seconds upon switching would help give the player more time to react and think about their next move.
For the comfort nodes, I think if you're sufficiently skilled you should be able to use them to weave through the asteroids. In my playthrough I just ended up trying to find a consistent strategy though since I found executing in real time and adapting to situations to be pretty difficult.
I think the level design is very good for 4 hours worth of work! They seemed well thought out and had a good learning curve. I think the aspect I liked most is that with just two nodes you can grow and shrink your radius arbitrarily, so maybe a level with just two nodes that requires growing and then shrinking would be a good follow up to the 5th level.