I do have a Super Tiger .90 converted to run gas and I like it very much. Normally I don't advise converting glow engines to gasoline because they lack cooling fin area for gas use, but I run it on an airplane without a cowl, and I make sure to never run it lean. (Yes, I know a properly designed and executed, cowled cooling system can be even more effective than an open engine.)

But, I think 20cc is a better all in all break point when considering weight, size of appropriate plane, scale effect, etc. That's just me though.

AV8TOR