For what it's worth I think a 556 can on a 556 is the way to go if you can afford to have both a 762 and 556. Most 762 are big for a 556 imo.
I have one Surefire 556 and 762 for my larue rifles. They work extremely well. I wager you'll be happy with the smaller 556 can on a 556 LT rifle (OBR, tOBR or tAR)