I try and keep the gaps close, but have also sealed the gaps in some cases. Can't really say I noticed a difference, but just about everybody agrees its a good idea. I have a couple of fast planes that I make sure and seal the gaps--would hate to loose and elevator or elevon due to flutter.

I handle training for our club and have seen some pretty large gaps in the planes some guys bring out. We always give the control surfaces a pretty good tug before flying a plane for the first time--its interesting how many times we have had epoxy hinges installed with CA, or CA hinges installed with epoxy. I have had some surprised looks when I tear off an airelon but then it's better to loose on the ground than in the air. It's better to be on the ground wishing you were up there, than being up there wishing you were on the ground.

Greg