Hi WC, yes appears to be an excellent little trainer and a rather simple build.

My all time favorite in a twenty size trainer is the Sig Kadet Soniorita a bit larger than that design but is stick built instead an likely a light wingloading yet. Perfect for any .25 and would work with a .20.

Only problem with a .20 is they are virtually extinct now with hardly anyone building that displacement any more so at least in my country at least a .25 would be the engine of choice.

John