Mark- sure, the halo drive cone is rigid, but it is attached to the motor with a spring between the cone and the gear that turns it. It has almost 360 degrees of "give" before putting crushing pressure on paint. The Egg relies on the elasticity of that propeller to avoid puttinf undue pressure on the paint- a cheap solution, but less effective. A sprung gear in the hub of the propeller plus cloding that caused it to tension would allow for force feed, but the sensor system is still going to wait for gaps, so without making some major changes, you're right, Eggs won't force.
LJ- I would like to see a sliding closure of the bateries, as used on the Revy, which would of course require new shells as well as a new door. There are probably a lot of ways to do it, but I like the tried and proven design. I don't think anyone has improved on that aspect of the Revy.