I don't normally reply to myself.. Just saw the thread on inverted prop hanging with the colletive stuff. Looks like ya'll have already talked about it, at least in humor. I really think it can be done!

Technical issues.. added weight with reduction unit / rotor shaft / head / 3 additional servos, firewall strength, rotor integrity (from higher RPM's and gyroscopic forces), having enough mixes, enough channels (I count 8 minimum), additional torque from big prop. What's missing?