I use 5.56 often, and I never shoot to wound. My targets go down. The argument that the 5.56 (while not perfect) is too weak seems to mostly be a big issue with those that have never had to use it, or those that aren't hitting their targets to begin with. Shot placement, folks.
I do not know why folks are getting hard ons over the 6.8. Unless you plan on persuading NATO to go with it (After that huge 5.56 fit we threw) .. it's not going to happen. A better bet would be to focus on getting the Mk 262 out to all and more trigger time for the troops. The 6.8 is not going to change the fact that they aren't hitting their targets to begin with.
I like this weapon, but it is a massive waste of time and resource with the 6.8. I myself, would not be firing any 6.8 rounds into live flesh anytime soon .. I value mine and my men's life to much to go around leaving "Hey! It's the Americans! Follow Us!" signatures all over the bodies.