That and cpwill's assessment that you may be taking away one of a Squad's machine guns for something that could stop because of battery power worries me. The whole point of the assessment that our boys are outgunned is that AK47's and old Soviet sniper weapons use a heavier round which needs a bigger cartridge to fire it meaning that it goes further and carries a bigger impact when it hits.
I loved the old 7.62 FN FAL, never tried any newer 5.56 weapon and frankly wouldn't want to somewhere like Afghanistan. Personally I feel we'd be better off with all the squad carrying more powerful weapons than having one team member have something like this. Just hope the UK dept of defense is too cash strapped to want any - nice though the concept looks.