I am not too worried about the initial cost, if its 100$ more than a 690 if they perform better, but for power consumption i have heard that the AMD cards are HORRIBLE on that and can cause a big power bill which would make it not worth it in the long haul.
So the 7970 is a single card, dual GPU, just like the 690? Ok that makes sense.
In the benchmarks it didnt look like it was 5-10% it appeared to be a lot more in comparison in most tests, but is Micro stuttering a big deal in these cards? I have heard AMD's cards are much more prone to micro stuttering and that is a big draw back to me.