Just to be clear, it's on the bottom of the wing, so the effect the split flap has on the wing is to create an upward reaction force from the airstream being deflected downward by the flap. It's only about 1/4 the wing panel and near the fuse, so it shouldn't adversely affect aileron response (I hope).

I guess if I were to go ahead an do it, the worst that could happen is it doesn't work and I've added a few ounces to the wing. I could even yank the servos and glue the flaps up permanently to remove most of the added weight. See how I'm rationalizing this?