At 352 gflops you probably won't notice much difference. Though it'll still be nice to see Nintendo IPs in HD.
360 never hit its theoretical flops iirc, there were bottlenecks that couldn't be overcome. Beyond that, a lot of flops were wasted trying to do effects that are cheaper to do in DX10.1/11... I'm not going to even go into efficiency differences between those architectures, but esspresso should comfortably out perform Xenos by more than 50% doing the same things... It is a matter of devs focusing on the platform enough to pull the extra performance out of it.
Matt, the only thing I can think of is Shader Model 4.1, R800 used SM5 iirc, so that would be a good reason to keep calling it R700 I guess.