I'm still partial to the M16/M4 family being that I've carried one in a hostile country, aswell as an M14. (We can add many hours behind a Barret M107 too) But I can say a decked out M4 consisting of a TA31 ACOG, PEQ-2, and a Surefire Tac light, it gets heavy after hours at the ready. The big improvement I like with any of the ACR/SCAR series, is the ability to swap calibers. If I knew I was in an over watch type mission, 7.62 would be my selected bitch maker, where as something in the way of CQB, I may opt for 5.56, or 6.8 if at all possible. I will say the adition of synthetics and plastics, will lighten the load significantly, not to mention, overall weapon movement. A lighter rifle is easier to control and move with. We'll see once these weapons get into the hands of those putting them to good use. I know I'll have to stick with another M4 for my year long mountain journey.