The 28 is hard on barrels, 600-800 rounds is what I'm hearing a lot.
I only have 200 rounds through my 300 NM so I can't speak to barrel life, I will say though I'm using a lot of powder for the velocity I'm getting.. it'll probably only go 1000 rounds.
215's are running 3060 with 89 grains H1000 (HBN coated), I was running 225's 2950 with 87 grains. 26" 8 twist barrel.
It's shooting extremely well with 215's, but for the amount of powder I'm using to get that velocity I'm not overly impressed.
I'd go 30 Nosler or 300 PRC, you'll be right on the heels of the NM with less powder.