I have a Noveske barrel that building an upper around. I was looking at getting a MUR A1 for my upper until I started to see the prices that people are charging for them and the wait is out of control. Are they worth it? If so what makes them better than a CMT, BCM, or a Rainer Arms Upper? I have not found anything that says why they are so much better that all of the rest. Does anyone have any info on this? Thanks.
They are stronger than standard uppers. They help with accuracy so you really only need one if you plan on making it a percision rifle.
There is an article on the MUR at MilitaryMoron’s website here. I found it very insightful.
I do agree that the advantages of the MUR are fully realized only when paired with a precision barrel. What kind of upper are you building?
If the MUR is hard to find and your are still set on a billet upper, you might want to consider the LaRue Tactical Stealth upper. The styling of the Stealth is more traditional and subtle than that of the MUR, but both uppers share similar advantages.
I am building with a 12.5 Noveske Crusader. If precision is the only plus I guess I
can forgo it with an SBR build. 
I read the MM review and if it is just “built to spec” and not a true precision receiver
than I might just go with a LaRue Stealth or a Colt.
Thanks for the input.