I'm havin a toss up right now between the two. I really want one in desert tan to match my rifle which would mean the 556. With the 552 I cannot get that but it's reasonably cheaper, battle proven, and also seems as though batteries would be easier to come by. Both are night vision compatable. Is their a height difference that would be a difference with my BUIS or what would be the trade-offs from those who use them?