I'm OK with it as long as they don't choose Vulcan or their ilk to order replacement parts from. Most ground troops still have the M16A2's, which work well with the DI system if they are maintained. The problem I think most troopies have with it is when the armoror gets a DILLIGAS attitude when it comes to his part in the maintenance of the weapons. When I was stationed in combat arms units, we had armorors who didn't lift a finger on the maintenance, and it showed. The bolt would go in the carrier like the gas rings weren't even there, and it was nothing to have worn or missing extractor springs. The whole gun felt like everything on it was worn out. There were parts on it I knew were from the Vietnam war. I didn't know there was a such thing as higher maintenance on weapons until I was in the Reserves and became an AGR. Then I saw weapons being maintained. One of the con's of going with a piston AR such as the HK 416 is they have a large percentage of proprietary parts that will not take replacement parts from the M16/M4 platforms. From what I have read, such a low percentage of M4 parts are interchangable with the HK that we would have to introduce all new parts to the supply system. If you are going that route, we might as well just start with a new design of gun altogether.
I think the piston guns have a place in the Special Ops units, such as Seals, Green Berets, etc., where they have to have a better reliability ratio, and the barrels are shorter. They are also not as ingrained in our supply system as the regular grunts.
For the regular forces, it may be more cost effective and sensible to maintain the M16A2's in the system now than to go after every toy available.
I am with some of the posters, though, and beleive the numbers of what was needed were made up after the fact, to justify not giving the ground troops a new gun after the DOD has spent so much to give the flyboys their multibillion dollar stealth toys. Just my .02
"Democracy is two wolves and one sheep voting on what to have for dinner.
Liberty is the well-armed lamb contesting the vote." - Benjamin Franklin