Took me a while to dig these up again.
EDIT: On topic of Machine guns, what do you think about the changing designation from Squad Automatic Weapon to Infantry Automatic Rifle?
The whole debate of this comes from the military's further need of an automatic weapon that was more lightweight and reliable than the standard belt-fed. Long before this, ARES tried solving the weight issue by developing the Shrike 5.56 which was essentially a belt-fed AR-15 capable of feeding standard STANAG magazines or SAW Belts. It also had the advantage of using an AR lower which soldiers were more familiar with.
Personally, I don't understand why this weapon wasn't introduced into military when it was first developed.
Now you got the H&K developed M27 IAR, which is in essence a reconfigured HK416, designed for the USMC. Coincidentally and funnily given the same designation as the 5.56mm belt links that it does NOT use because it is magazine fed.
I would've liked if the USMC had gone with the Ultimax Mk. 4 as their IAR but it's understandable that they took the M27 over it seeing as it's functions are that of an M16/M4/AR-15, thus saving time on weapons training as soldiers are already familiar with it. However, it lacks the ability to switch between standard magazines and high capacity belts like the Shrike can.