Well, they're most definitely all reference designs so they'll be identical. It just comes down to the resale value and the support the brand offers afterwards...
I'm gonna try to get a hold of someone's Vista HDD so I can run Vantage for a bit. I would really like to do more than Dx9 on a card of such high caliber. Also, I'm limited to 1440x900. I can go upstairs and bench at 1920x1080, also. I'm working on picking up a monitor, but the one I want is 300 and I want it to go on sale.
1920x1080 is good, I can do that res too, and I expect it's the resolution our two cards will be the most widely used at.
Also, Vantage is DX10 I think.
You probably should try to steer us away from Vantage anyway, the HD 5xxx cards rule over the 4xx cards there.