I'll go add official 8 and 16 wide support in a bit, should be useful on, say, AVX if you manually enable CPU mining in the code. SDK 2.6's cpu compiler apparently has gotten a lot better from what I've heard.
So does that mean that is the best for 5870 cards ? Or stick to 2.1 or 2.4 ? I am quite confused as to what the best SDK / ati driver combo is ATM.
Notice I said CPU not GPU. CPU mining still sucks altogether. 2.1 is still best for 58xx cards.