I fiberglassed (very easy to do, fiberglass cloth strip and CA) a 3 inch strip all the way around my center wing joint. took alot of diheaderal out of it and replaced the rubberbands with big ole nylon screws (same one my buddy with a 30% extraa uses)

I have thrashed my avistar and so has some serious acrobatic flyers without a hint of wear or tear.

so I recommend.

1. 3 inch fiberglass strip all teh way aroudn wing joint.
2. reinforce major stress points inside fusalage. (epxoy here and there)
3. for funner flight- take some of teh diheaderal out of the wing. (less stable but very cool for acrobatics)
4. ditch the rubber bands replace with nylon screws for wing mounting.
5. watch teh tail feathers-under extreme use I have witnessed some fly off of avistars.