IMO it depends on the map which is played.
e.g. in beta 1 maps you can have 16+ people on Facility_classic without problem but the same amount of ppl on Facility Frontzone will result in a spawnkill orgy.
But i think most admins can decide by themself which server setup will be the best choice. So if the server is limited to 8-12 ppl the mapcycle should prefere smaller maps and if it's up to 24 ppl it will be a good idea to prefere big maps.
I don't know much about the server admin stuff but it should be possible to write a server script which makes the mapvote related to the playercount, so if there are 16+ ppl the next map will be choosen out of the big ones.
Maybe it can also start a vote for a bigger/smaller map in midgame, e.g. there are 3 ppl at the start on a round it's a small map and everything is ok. after a few minutes 9 ppl have joined and the map is crowded well.
The server starts a question vote, change to a bigger map <Yes> <No>, so it's still up to the ppl.
The midgame mapchange could be arranged that way:
facility frontzone (10+ ppl) >> Facility Backzone (16+ ppl) >> Facility (full)
Stack/Basement (12+ ppl) >> Library
maps without a conterpart >> another big map (mapvote?)
But i think this is a task for a server admin (isn't it, B@d?)
