Rumor has it that the military version of the mr556, which is essentially the same gun except with a chrome line barrel and select fire, is a favorite of spec ops and was used in the Bin Laden raid.
There are comments up thread from people who actually
are in the SOF community. Basic upshot is that, marketing hype aside, the HK416 hasn't been a resounding success, and it's only caught on with a niche market within the special operations community. So it's not a "favorite of spec ops." It's a weapon used by certain end users who have requirements for a weapon that's marginal on accuracy but good to run with suppressors or very short barrels.
To be fair, it is more successful than HK's last SOF offering, the Mk 23, but that really isn't saying much.
Their guns are expensive but they also put tons in reasearch and development as well as quality control.
Which explains why they put the safety on the MP5 and other weapons of that generation where no one without orangutan hands can manipulate it without breaking their grip. Or why the USP series of pistols has such a remarkably high bore line. Or why they seem to have deliberately designed the HK416/MR556 lower to not be compatible with PMAGs but to allow better use of the "non firing hand grips front of magwell" shooting technique that no one with any training had used for a few decades. Or why they used such cheap steel in their "improved" AR magazines that when my unit got them we were literally having misfeeds due to bent feedlips the first day we took them out onto the flat range (to say nothing of how the "non binding follower" on them would, well, bind more frequently than USGI aluminum mags in good condition).
I will say that I used to be an HK true believer when I had zero experience with their weapons. Some time on the range with MP5s, HK53s, and HK416s pretty quickly illustrated to me that while their stuff isn't bad, it doesn't live up to the claims of the HK propaganda machine nor justify the price tag.
There is a finish comparison pic with a colt:
What does that have to do with anything relevant to a fighting rifle? If they spent more money on quality barrels and consequent accuracy rather than trying to make their product look polished and pretty externally maybe they'd do better with serious shooters.