I plan to pick this back up soon. I haven't played since I recently moved. I'm sort of worried that the wireless XBox connection will be a dropoff in reliability from the wired connection I used to have.
I 1Ked L4D1 (never got the expansion), but couldn't be bothered with 1King 2. Expert, while certainly interesting, always leaned a bit more towards annoying and frustrating than fun.
And calling this redundant is understatement of the year, but L4D (1 & 2) VS is just so amazing. I never liked online play much. The only game I ever really played online multiplayer with was Return to Castle Wolfenstein (Beach = best online level ever). But after playing campaign and then VS on a whim, I was hooked.