Excellent feedback! Thanks!
I decided to leave the z-plane accessible in order to raise the stakes and allow players to fall off the "front" of platforms when being hit by falling blocks... But maybe that wasn't necessary for the movable blocks. They are full physics bodies and the simulations are glitchy at times. If I had more time I would have implemented more hardcoded move logic, but I did this in a few days using the beta.
Every agrees with you on the double jump. I need play testers next time around!
thanks again!