Make sure the grind fits your swing and the conditions you normally play.

I did the same switch you are thinking about but with 58° heads. My old SM5 58M was excellent around the greens, but I had a harder time with it on full shots because of the rounded sole. I have been playing with an SM6 58S for about a year now and I find that it is better in the bunkers and crisper on full shots, and it still handles as well around the green. I would suggest seeing a fitter or just testing both models of the SM6 and then decide which one fits your style.