It seems like I sat around there for the Tommy reunion concert last year. I don't remember it being particularly steep, but that kind of thing doesn't bother me, and I've never been in the mezz at the Rodgers. I don't think it was as raked as the mezz in say Studio 54 though if I remember correctly.
If this is your first time seeing it the seats don't really matter. The show has so much energy when it kicks in that you could be knocked on your butt if you had a seat in Bryant Park.