Here`s a Q? is there a rule about modified engines? Bob @flyfreeflight.com does a nice head job mod on TeeDee020`s that gets them up to 29k rpm if thats legal for you guys thats the hot ticket to a head start on winning
Allowing guys to do whatever it takes in terms of time and money to win is what kills participation. Not everyone owns a machine shop or is willing to pay a machinist to stay competitive. The biggest uphill battle is to keep the playing field as level [and simple] as possible to encourage as many guys as you can to take part.
Once you establish a "hard core" group of competitors, then that is the time to talk about an unlimited event that could be run after the "entry level" event has been flown.