All I want is a mod for Left 4 Dead 2 in which you choose one of the Team Fortress 2 mercs as your character instead of the normal survivors. All weapon pickups just become ammo / metal, etc. Not quite sure if being downed should just be eliminated, due to easy healing from the medic, the dispenser, the sandvich, etc... But the respawn closets should function the same.
I don't care if it breaks the difficulty curve or dialogue, I just want it to function and be fun.