So are there duplicate characters and is the difficulty upped with 8 players?
Yeah, on mine at least, the lobby is disabled (lobby only supports 8 players) and when you join the game you get assigned a random character. We play versus, so there are more infected players too. I don't know how well it would hold up in tournament or other rigid setting, but for casual play, it's a chaotic blast. The survivors rarely reach the safehouse in my games, so it's mostly a matter of trying to make it as far as possible, then switching sides and trying to prevent the other side from making it as far. Most of the time, with some consideration to team balance, the finalscores are fairly close.
Note that my LAN parties have a lot of casual gamers and not many play FPS, so take that into account. I try to keep the game selection more arcade/action type games with low penalties for dying (short downtime). L4D2 is the most "complicated" thing we play, but even the ones who are not very good at FPS's really like L4D2. It's the highlight.
If anyone is curious, games we play include:
- Babo: MadBalls
- Garrison Gang 2 (2D side scrolling de-make of TF2)
- Galcon Fusion
- Armagetron
- L4D2
We used to play DOTA, which was a lot of fun because only one person had ever played it and we were otherwise all equally bad. After about 4 or 5 parties I had to drop it though, because skill stratification started kicking in and that game is very frustrating when skill levels are not equivalent.
Also note that I have a mix of macs and PCs, so everything on this list is multi-platform, and all of these (except L4D2, which can be fixed with modding) support at least 12-16 players, if not more. My parties usually have 8-12 people.