nVidia vs. ATI under Win7 x64 in TvT - Large Differences?

Question for your development team and others that have played with the beta release:

Are you finding any kind of performance discrepancies between nVidia-based systems and AMD/ATI-based systems running under Windows 7 64-bit?

On the subsim.com forums, it seems that users of nVidia systems under Win7 x64 get staggering frame-rates with ZeeWolf's mod (50-65 FPS), but users with "more powerful" ATI cards (such as the 5870 and 6850) get LOUSY frame rates, such as 9-15 FPS. CPUs behind all systems are basically equal (3.0 GHz+ Intel i5/i7).

Before spending hundreds of dollars on an nVidia card with just a "hunch" of evidence, I wanted to know that your development team can comment on with respect to this question? I wonder if nVidia's drivers are better tuned to the demands of TvT?

I know this has been proven in other games, such as Civilization V, where nVidia cards hold nearly a 2:1 lead over "more powerful" ATI cards - I wonder if TvT has similar effects. In Civ5, otherwise equal cards in nearly all benchmarks, the GTX 570 and ATI 5870 get vastly different performance results - with the nVidia card earning about 60 FPS while the ATI card struggles to get 35 FPS.

Any insight would be much appreciated!

You've seen my frame rates for MMP7 in the 'More FPS' thread on this forum. I'm running an i7-930 Win7 64bit and an ASUS EAH5870 V2 at pretty much maxed graphics settings. I doubt the equivalent N'vida would be much different.

Ok, thanks for the reply. Was just curious. Have seen wildly varying reports of FPS elsewhere and was trying to zero in on the issue. I might try an nVidia card anyway just to solve my curiosity if it doesn't cost me too much $$$.