Wing loading and wing taper
 

I get the feeling the problem with most ARTFs are that the wing loading is too heavy for 3D. Its the same problem in pattern. Some of them like the 3D Giles are really light and work well. I have a Giles, Synergy and UK Freestyle (modified Majestic 14 oz lighter) all have very light wing loadings and that makes all the difference. The pro pattern planes are built light and strong.

Also I don't like constant cord wings, they give problems with snapping, spinning and knife edge. Anyone else have any comments?