I'm also buying a 560 Ti within the next week, so I'm researching heavily.
Like most people I'm leaning towards the MSI N560GTX-TI Twin Frozr II/OC one as I really can't find a reason NOT to get it.
But I have been looking at this card
Palit GTX 560 Ti 2GB
I will NOT be upgrading again for quite some time so that much VRam would prevent a framebuffer bottleneck when Elder Scrolls Skyrim comes out. Sure, I could get a 1GB 560 Ti that's clocked slightly higher in other areas but that would mean nothing if playing at 1920x1080 in Skyrim would need a bigger framebuffer as going past what your framebuffer supports will instantly hammer the performance down. So quite possibly this would be a better choice as I expect Skyrim at 1920x1080 on average settings to break the 1gb framebuffer.
It's definitely something to consider if you won't be upgrading again for at least a couple of years, also depends on what you plan to play.
Though if you're able to SLI then everything I said is moot
on some night tracks, i cant even play nfs shift 2 without dipping down to the mid 30fps range... which is horrible looking on fast paced games. and skyrim seems to have a lot more going on.