Modern Warfare 2

[rossmum]

Matchmaking tends to find the first available player at any given time to join your merry group, and it tends to ignore ping as long as your live in the same country. This means that someone with 10 torrents running and crappy DSL could join your game, and due to the peer-peer structure of the match, he will bring the entirety of the game down to his speed.

And then they get voted out, unlike a dedicated server with AWOL admins.

Also, L4D and MW2 are two completely different games. L4D is more of a cooperative game that requires full servers to be played correctly, while MW2 does not.

Doesn't really make much of a difference...?