Pio, There i know you told me about you using Sapphire Trixx for your Overclocking. Sapphire trixx's support for the 7970 was programmed before anyone knew that the 7970s have leakage binned asic's, so its base voltage is 1750mv. They have NOT been binned for better performing cards, they have been binned to run at different stock voltages depending on chip quality. these vids range from the higher quality cards running at only 1050mv on stock to the lower end cards running at 1750mv. MSI Afterburner allows for the full range of VID control whereas Sapphire Trixx does not. Most people have issues putting their cards over 1200mv on air so this would give you a very limited window using trixx unless you put the card under water.
As far as low fps/stuttering issues go ive seen alot of people having similar issues when switching over from nvidia cards and its usually something the nvidia drivers leave behind, which is why you should use a cleaner of some sort.
After upgrading from my 5870s I have encountered ZERO issues with any of my games.
AMDs website even listed for the latest driver update that a known issue was the game "just cause 2" hanging on start, but i can play it just fine
I do hope they release some certified drivers soon though, not that it really matters much.