Hi Teo,
I tried David's patch files a while ago without success. I had Xen compiled with the patch files and my GTX 460 VGA BIOS rom, but I got the same as you, either a BSOD or Code 43 in Device Manager.
You sound plenty competent, but it's important to remember that you are pioneering a technology that for consumers is still in its infancy. Very few people are testing this with consumer equipment, so finding results seems to be a rarity.