I use 18" and 20" crashes live, but 14" and 16" in the studio. The big cymbals are so slow they take forever to open up. Even with gates I cant get my bigger cymbals to speak properly in the studio.
I also use Sabians live and Zildjians in the studio, so that may be part of the difference as well. I love the sound of the bigger Sabians to the naked ear but the A customs seem made for the studio.