One aspect of the Remington ACR which I have not seen discussed online is that it is being offered by the company with a variety of lower receiver designs.

From the Remington Military catalog.

The standard Bushmaster / Remington ACR receiver is made of polymer with a moulded pistol grip. Remington is also offering another lower receiver that can accommodate an AR-15 pistol grip. See the above image.

An employee of Remington MPD told me that they also plan on offering a magnesium alloy receiver to select customers. I suspect that Remington would be willing to offer a lower receiver made out of diamond encrusted platinum if a large enough military customer required it!

If the Bushmaster ACR sells well, aftermarket lower receivers could bring in a lot of additional revenue. More than a few customers would be willing to hand over fistfuls of cash for a fancy all-metal lower receiver so that they could differentiate themselves from the crowd.