As has been mentioned, a properly glued toghether wing is very strong. If the interal structure of the wing is not glued well, then all the epoxy and fiberglass in the world over the center joint is going to do no good.

I have only built two kits as I am more of the ARF type, but one thing I did when building these 2 kits (SSE's, both of them) was to add carbon fiber tape to the top and bottom of both spars in both wings. After the wings were built and before they were covered you could not twist or bend them. Fold, spindle and otherwise mutilate would probably have been a different story.

The only ARF I ever glassed was a 4*40 and only because of some of the stories I was hearing about wing centers on planes on high stress manuvers were snapping. I now know that this was not really needed. I now have a 4*60 that has not been glassed and I fling this thing around as hard as I did the 40 size and probably harder as this plane is my "grab and beat the heck out of" plane. I have several other more aerobatic and 3D capable planes and I do not through them around as bad a I do the 4*.

As an example, a high speed snap roll on a Funtana90 may very well rip the plane apart, I do them on the 4* and that is with an OS91FS turning a 15X6 prop so it's not that slow.

As a matter of fact, go over to the Funtana90 thread and you will find that the early models had wing problems and they were blowing apart in the air at slow to moderator speeds flying straight and level. Now some of the was due to flutter but there were issues. Mine had right wing ribs broken right out of the box. I am sure this would have lead to the planes destruction if I would not have checked.