There's a 16,000+ post thread dedicated to the next-gen consoles on a UK-centric non-gaming forum I visit, and based on what's being said in there I'd say most casual gamers who mainly play CoD and FIFA are sticking with Microsoft. Main reasons generally seem to be friends list, achievements and preferring the controller.
Interesting to see if the strong US and UK base continues for Xbox.
NFL in the US at least and COD as usual. Are the masses loyal? Does a gamertag, gamerscore, friends list mean that much?
Could be stick to what you know but a 100 quid less, who knows.