Shogun,
One would think that your powerful metal geared digital servos help prevent flutter but UCD's don't seem to flutter even when Futaba S3004 standard ball bearing servos are used all around. In fact, of the six UCD's I've seen fly none have a flutter problem. Two of them make me cringe because they are flown at full throttle with OS 91FX 2-strokes for most of the flight but nothing ever happens. I'm really gun shy about flutter.
By the way, that SIG Cap 231EX you see in my avatar lost one aileron due to flutter and the other aileron stripped a couple of teeth off a gear in a Futaba S9304 core-less ball bearing servo. Caps are not easy to land with one aileron missing and the other one partly deflected and non-functional. It has since been repaired and is flying again with no flutter. And yes you will enjoy yours. It has typical Cap characteristics, a great snap roller, flat spinner, tumbler, knife edger but not all that easy to hover.

southern_touch9,
You are right, a wide gap will not cause flutter on every airplane every time. It is also true that closing the gap and sealing it will not stop flutter on all airplanes every time. Some planes require more drastic action.