When I plug both specs in with my current gear, 15/51/5 comes out better, but only with they typical 10 and 25 man buffs. If i minimize the buffs to basically GOTW, Savage Combat, and Might set to true, then 7/51/13 comes out better. I'd say in 5 mans 7/51/13 is better, but 10/25 (i.e. raids) then the 15/51/5 is quite a bit better. I didn't realize that until you brought it up and I tried various buff combinations. I been running 7/51/13 myself because I don't always have buffs enabled in the spreadsheet, and in that case 15/51/5 doesn't "appear" to be as good.