The first batch of 2k10s are fine. The current batch of 2k10s are roomier and I go down half size. I stay with my true size in the CBs 1.3, 2.3, and 3.3. I went down half size on the Vapor 7 and 8s.
I wear only Nike tennis shoes and Nike running shoes. My normal size is a men's 9.5. And I wear the Nike tennis socks - one pair.