Hey Sascha,
I’ve been able to get it to work relatively well. I experience some kinks in playback in the color page, but nothing critical.
I haven’t looked into the 680 card, so I can’t comment about it, but for the most part, my 580 seems up to the task so far.
If there was any advice I would give to a hackintosh newbie (which I consider myself being also), it would be to make sure you have all the Motherboard BIOS settings correct. A LOT of problems stem from incorrect BIOS settings. Do your research on TonyMacx86, which is an amazing resource.