The group server seems to be working well. Unfortunately, it seems to always default to coop, so if you just click on it in the group servers, that's what you get.

In theory, you can get other modes by setting sv_search_key ZHABrains from the console and then starting your lobby for whatever gametype you want. Make sure to clear the key later or you'll never get any other servers. You probably need to set it up as "unofficial dedicated".

Other cool stuff is the ability to call a vote to pause the game and to play single-player vs without it shutting down and to force the survivor bots to do things like leave the saferoom (in case you want special infected practice).

There's also just a bunch of funny mods like making it rain gnomes and turning down gravity. Not that useful, but get me your steamid if you want me to set you up as admin so you can play around.