Okay - I misunderstood your comments
Some guys with Mk18's I know use S&B's, more than a few are using TA31DOC's etc
The NAVSOF guys doing VBSS stuff dont really need to worry about issues at range - so the majority of those guns have Aimpoint.
Honestly if I had more uppers around the S&B would not be on the 10.5 - but I've donated 3 uppers to the war on terror - and they dont come back -- and I lent another upper to a buddy in 1VP to shoot while I was in Iraq.
So this is about my only AR (well many lower - but only two uppers here).