I pushed a hotfix a few days ago to add more checkpoints, I'm sad that it ended up preventing you from finishing the demo!
I have pushed another patch just now that addresses that, as well as several of your other notes (Air control, sprint by default), but since I have been moving on with ambience tests, it might not run as smoothly.
Thank you for the writeup - our main focus at the moment is core mechanics and movement, so the feedback is very much appreciated! I think we'll have a lot of your other notes addressed to some degree for next DD!