I have an '05 with the "600" engine. Buy it. I haven't had one regret about this one, done some heavy towing with it, and I have no idea who would ever be able to tell it was a "different" engine than the 610.
It was all a numbers game so they could jump ahead of Chevy's 605 Duramax.
While these "600", "610", and "605" numbers on the Dodges and Chevys refer to torque specs, I have been told by reliable sources that the Ford 6. 0 "570" designation is making reference to the number of expected trips to the dealer during the life of the engine.