I have had a few guys ready to race the warbirds with us, until I told them there was a B/O. That killed the deal for them. From my influence of racing, there are more anti B/O guys than the opposite. But everybody wants their own thing.

If you regulated it with specific ARFs (no custom planes) and engine ranges, like class A uses 115, class B 91 , class C uses 70 (these are just 4 stroke examples) then let em race, the costs control themselves.
Seems the manufacturers have listened to the distributors over the last few years and we have seen several F1 type planes made available.
So Id think there could be a good variety to choose from. You select the kits or start a kit list that is approved. Add to it as necessary based on availability and new planes.

Would this class draw 60 pilots- no. But would you want to?
If you made this a stand alone race, then yea, you would, but if you added this to an already established race, then you wouldnt want too many entries.

As far as Q40 and Q500, most places are 3 pole races. I love the 2 pole Q500 stuff we do here in Utah, but I havent heard of a lot of those type courses.

6 to 10 planes at a time racing would be great for the economy Jeff and you may become the sales rep for these distributors.

5 is plenty and keeps things moving fast enough.

Could you see 10 planes on a short course- it would be hilarious. How would you like to be a pylon judge or pickel pusher?

You are thinking a good line of thought here, so just keep it going and I would join you, as long as I get to win, other wise Im taking my toys and going home.