I think the fake American accent gets called "mid-Atlantic" simply because it's metaphorically stuck in between the two countries.

Joe: My feeling about a Briton trying to sound American, is that he/she is trying to be egalitarian.

That strikes me as a bit of a strange reaction. Apart from anything else, do Oasis or Arctic Monkeys sound snooty to you?

For someone like me, trying to sound American would be like trying to sound Australian or South African: fake. Being egalitarian or snobbish wouldn't come into it.