Hills are cut about 1/8 inch proud of center. Add a leather strike plate and they're probably 3/16 proud of center. I'm a bit surprised that the 600s fly well with that much weight on the front end. I'd expect a 500 Axis with 275 grains up front to shoot well out of that bow. But, it is what it is.
I, too, cut to length and add front end weight as needed. I cut my arrows to 29 inches BOP and can shoot 600s and 500s out of my 45-48# ASLs (at my 28-inch draw length) -- the 600s with about 150 grains up front and the 500s with 250-275 up front. I am shooting low stretch strings, which require a stiffer arrow than dacron. My elk set up last fall was a 400 Axis shaft with 350 grains up front for a 650 grain arrow out of my 52# ASL.