I am considering the same dilemma. I imagine we'll have benchmarks tomorrow and know for sure, but I'm speculating that the Air 13" will be faster. We know that the RAM is slower though - so I'm hesitant to call it a slam dunk.
According to Geekbench in CPU performance for 64 bit single core the 13" Air gets 3228, 1.3Ghz Macbook is 2637. So with 10% performance boost, that's 2900, still slower. The 1.1GHz was 2299, so with 10% improvement that's 2528.
I don't see how the new Macbook will be as fast as the current MBA 13". Not even the top of the line Macbook.
That's just CPU, but even faster memory won't close that gap I don't think. GPU? I have no idea.
I should add, I'm still tempted to get the Macbook vs the MBA. I'd like the speed ad flexibility of the MBA but I think I'd miss the horsepower. I'm half hoping that I'm totally wrong and the new Macbook somehow is faster than the MBA 13". Then that'll be much easier for me to make that decision.
