Don't know here, but when I helped cut cores here in kc we always set it up so that you would have a flat top of the wing with a tapered up bottom, essentially dihedral. Washout is a twisting of the wingtips and I think that's what you were implying, but we built ours straight. I'm flying SPAD's now and swapped from Gremmys to SPADs after my last midair snowshower. You can build a Sickle (gremmy style wing) or a Flipper(inverted with some change which really isn't a combat-able ship) for a fraction of the work/cost.

However, it still doesn't change my wishes for nice 25 powered Gremlin, or one with a 36 which was monster power and still pretty light.