At the request of @swarmik, who's also a member of this forum, I ran his GPU benchmarking software "GPUbench" on the XVR-4000, in order to gauge it's actual performance.
To quote @swarmik, "It seems that this was not a universal hi-end solution but rather just something for very specific market".
It seems that really high quality antialiasing is this card's strong point, as it renders a beautiful output (better than that of the V12), when rendering Quake3, even though it doesn't have the best frame rate.
Here are some examples of what one of the tests looks like:
The initial results were dismally poor, as we were initially unaware that the XVR-4000 was setup to automatically render with 16x forced antialiasing, which resulted in rather poor performance in the initial battery of tests.
After disabling the forced multi-sampling, the XVR-4000 obtained the following results:
Here are the results from the Tezro's V12, for comparative purposes:
The results of these tests will be reflected on his site, where you can too download his benchmarking software. Here's the link to his site:
http://swarm.cz/gpubench/