I have a 30 Nosler, and no longer shoot my 338LM or 300WM rifles. Cartridge is a better design, more efficient cartridge than the 300 PRC. Plus there are 3 or 4 companies providing quality brass. I'm launching the Berger 230-gr Target Hybrids at 2930-fps. Not saying the 300 PRC is any slouch, just believe the 30 Nosler is better.
If you're already running a 300WM, I would stick with that. Great cartridge, but in my opinion, the cartridge doesn't provide any benefit if you plan on shooting anything heavier than a 215-gr bullet.
As far as barrel life, a 300WM barrel will last longer than a 7 SAUM or 7 RM, as I have first hand experience. Won't be getting rid of my 300WM's anytime soon, and will be building another 7 SAUM as soon as I get an action ordered.
Lots of cartridges out there, and they all have pros and cons.