Very nice! You didn't have to jump through nearly as many hoops as I did to get TAA working on the GTX260.
I'm not familiar with ATI's AA modes, but I remember reading that 'performance' TAA mode takes half the number of samples on transparencies as the selected MSAA mode. If so 2xMSAA + Quality TAA should equal 4xMSAA + Performance TAA on transparencies. 4xMSAA + PTAA sounds like a good deal.
Please do tell