Simple is best or you take the fun out of the hobby. Still you might consider dividing the .90 size engines from the .45 size engines. I don't think 3 classes would be too big of a problem. I have (3) .90 size models, (2) .50 class and (1) .32 size. All three sizes have completely different speed ranges.

I think the main thing is to get together, fly fast and furious and have fun!

Bob Holmes