another one of the reasons people are happy to have thick square trailing edges is that modern rc aircraft have an excess of power to weight. Drag is not an issue unless the engine flames out - and most people don't seem to worry much about glides back to the strip dead stick. (model) Gliders don't have have thick squared off trailing edges - so why build them into powered planes?

Also, the flutter argument sounds pretty weak to me. The only reason I see a square trailing edge being better than a tapered one for flutter is that the squared off trailing edge is likely to contribute to a stronger/stiffer control surface. Having said that I taper all my control surfaces and don't get flutter and get way better glide performance gliding deadstick than anyone at my club flying artfs, rtfs or any kit. Can't help thinking eliminating drag during design helps with this.

And: The argument that full size is not the same as models is also pretty spurious. OK yes they are different - but you know what? most of the difference is that because reynolds numbers are smaller, model performance is worse - worse L/D, more unpredictable stalls, more flow separatation, hysteresis loops - non-linear lift/alpha. So the thing to do is to take aerodynamics just as seriously for models as for full size. Even with scale effect considerations, models are more similar to full size than they are different. I can't help feeling the luddite contingent of this forum don't want to talk about what is actually happening with airflow around our models because it makes their brains hurt.