I haven't read this thread, mainly because I can't be bothered, but I thought I'd add my 2 cents anyway.
I'm British, I just want to say that before anything else. And here is why I dislike Americans on Xbox Live. The majority of Americans I get matched with on this game a 12 or 13 year olds who shouldn't be playing this game in the first place, and on top of that, they're really loud and annoying. Add to that that the sense of anonymity makes them unspeakably racist. There's just no need for it really. And it's not just kids. You get alot of Americans who just rip on us Brits for no real reason. Sometime I'll just be sitting in the lobby talking to my party and all of a sudden a group of obnoxious Americans join in and start ripping on us for being British. When I asked one of them "Why do you hate the British? It's not like we've done anything to you.", his response? "'Cause youse got bad teeth!"
Normally, I don't have a problem with Americans, it's just these two groups of people that piss me off to no end. At least half of my friends on XBL are American and I get along with them fine because they act normal, and there's why most people hate Americans. You, as a group, don't act normal on Xbox Live.
And another reason I hate playing with anyone who isn't European is because of the lag. When I play with Americans they can be a full 2 or 3 seconds ahead of me, and I'll die stupidly because the guy who killed me hadn't come round the corner yet on my screen. It's stupid. I'd really like some British servers, but I don't see that happening anytime soon.