Hey, all it takes to be good at 600 yards is hundreds and hundreds of rounds of practice, and a really great ability to dope the wind. Isn't that what all of us do?
But is that critter at 575, or maybe 625? There's a fair difference in the trajectory, maybe a foot, foot-and-a-half with a 7 Maggie.
And "just a breeze" will give you some five feet of wind drift...
I've never messed around beyond 500 yards, but it's a bunch different from the easy stuff of 300 yards on in.
But, yeah, the Maggie will do better than the .308...