With the current system for servers it'd be a bit impossible to have total control over any servers we would have. Most private server owners shut theirs down due to this, even some cases of start in versus mode, have a level change and they aren't on their server anymore. Not to mention theres no real server lobby, no good way to advertise in the server. The whole community part of L4D is lacking.
I'd say its a great game, and promote it, but until the community gets raised up a bit I'd say hold off on investing too much.