I'm not familiar with the 17" AA Rock specifically, but in my experience 17" is right on the edge of being a little too small for that much weight. If you really smack your cymbals I think it would work fine, especially in a live setting.
But honestly, I don't know if it's going to blend with the Paistes at all. I personally don't care for mixing crashes that are B8 alloy and B20 alloy in one set up. I'd say if you like contrast, go for the Sabian, but you'd probably be happier with adding another size or another weight of PST7.