I wouldn't pay for a single one of these, simply because it's been the standard to be community-driven (in terms of competitive play), or because paying for virtual items in a competitive scene is fucking retarded (virtual goods).
As for the ladders and such, I don't want those in my shooters. Not at all. Keep it to the comp scene. Anybody who has spent some serious time playing BC2 on the PC can attest to the fact that stats have ruined the team play aspect of the game. The majority if people are so concerned with their KD:R, that they NEVER take chances, leaving any Rush maps a jumbled, confusing and frustrating mess. Objectives? nah, I'll just sit in this bush and pick off whoever comes in my view. That's the overall mentality.
And generally, I find even charging for map packs the way just about every FPS does it to be pretty weak. If you are going to pump out new maps, at least make a decent handful instead of 3-5. 3-5 new maps, which will universally always have at least half of them being terrible, only allow the longevity of replayability to stretch out so much, and the amount of time they take to push them out is atrocious.