I've been playing L4d2 quite a lot in the past few weeks. I have left 4 bringe moments every now and then. But when i play in Vs with only 1 other player usually my room mate against a team of 3 or 4 we always win. I think left4dead2 could use a exp system or a ranking level system so you can get into games with people around the same skill level as you, rather than either someone way lower or way higher. For example they could give you a survior level/rating aswell as a infection rating. I think it would make the game more challenging at times.

meh

i agree my friend! you get grinding and boosting in any game where XP and level ups are available. but it would mean im not constantly gettin into games where the server shuts down cos everyones rage quit. 

I'd like a ranking system, as long as nobody abuses it.

It would make it more addicting to have an Exp system... not that it isn't addictive enough already but I just find myself wanting to level max in everything I play so yea I probably would play it more often if that was the case. 
 
I also have mixed feelings about the ranking idea, would be nice to not have any elitists in my game its fine if you are just don't tell me something like why did you do that there? Because I wouldn't have done it if I didn't think it was the best thing to do or if I make a mistake. Thats the thing that ruins it for me with my friends hah, every single server SOMETHING happens and someone has to make a comment. Like whoops shot my friend and now hes down... here it comes. We are laughing but they aren't haha.

I think an XP based system could bring some players back, including myself.