I need to spend a lil more time on the test server to make any suggestions, but it does not seem that Mega structure is as popular as I expected.  I really like Defection and there are a few others that said they dig it.  Honestly though there are probably a few more that don't like it than do.  I think goes back to the flag runners opinions v/s the spammers opinions so I think we'll never please everyone.  I play this game everyday and I still don't know what the hell maps are best for the server.  Maybe the best thing to do is balance out the CTF oriented maps (Necro, Rails, Defection, Mining Cave etc) with spammy maps (Anarchy, Arena, Shoebox).   Say like 10 of each and keep all the Std maps on for people like MTV and others who will only play stock maps.  One thing I've herd more and more people ask for if a Map vote that would not allow the same map to be played until 5 other maps (or something like that) were played first.  Don't know of one for UT3 but it was on the 99 server.