Assuming that you don't need the belt feed ability of M249 often enough to justify the weight, complexity and extra maintenance. . . Should the automatic rifle fire the same round as the assault rifle? A more powerful round should still be controllable with the bipod and heavy barrel, but is it worth the weight and logistic hassles?

On another topic - fire and maneuver at the squad level doesn't seem to have a lot of fans here. I can imagine why - how many enemies can one fire team suppress? Is there still a place for fire teams in an organization that's likely to fight as a single unit?