This is a FABULOUS airplane!

My only suggestion is: Remove the wingtips.

Goldberg lengthened the wing so it would be IMAA Legal, but it really restricts the roll rate. I was going to "Clip" the wing, but the Owner of CGP told me to try just removing the wingtips (They are about 3" long each). It made all the difference in the world. and it's easy to do.

Just slit the Ultracote along the tip and peal it back. Then break off the horizontal plywood tip, sand smooth and iron the covering back on.