I thought about getting one of those this winter, but I wanted retracts, so I ended up with a .45 WM P-51 instead. I'd love to hear how you like it once you've got it flying.

Speed alone is not going to cause wing failure, but high Gs might. If you like to fly in a smooth, somewhat scale manner, I can't see a need to even consider glassing the center. If you want to do all kinds of violent things at G forces that would never be seen in a full scale plane, then glassing the wing center may help. However, while glassing may protect the center joint you may end up getting a failure just past where the glass stops.

I've never had a wing fold up, ARF or otherwise, and I've never glassed the center of the wing. Some people insist that it's a matter of time for it to happen, and others say that's just hype. You decide.

On to the flaperons. I asked the same question when I was assembling my WM P-51. Some said they would be ok, others said don't do it. The reason for not doing it is using flaperons could lead to tip stalling. I ended up with flaperons, comes for free when setting up my radio for dual aileron servos, but I have not used them. If the plane isn't too heavy, it should slow down just fine without the complication of flaperons.