A game server has better uses for it's BW than providing a user with a map he forgot to download 
*Forgot* to download? The first thing I do when I encounter a new map (not for server bandwidth conservation I must admit, but for selfish "I can't be ****ed to wait that long to download directly from gameserver) is to disconnect, exit, and browse tremulous.info for maps. When I don't find them, well (which is why I'm answering to THIS post), just pisses me off...
OK, it's not all bad. What follows is fair and informative. Thank you.
The server protocol imposes a hard limit on the upload BW used for each client. That hard limit is the same ingame or during an auto download.
Poll