My opinion:
I own, and have loaded for a bunch of 28Ns. I run mine conservatively with a 195 @ 3084 for my hunting load. I have run the 195 as fast as 3175, or a 184 @ 3200+. I expect barrel life in mine will be about 700-800 rounds. I have seen barrels be toast in as little as 500 rounds. They are an awesome hunting round for elk sized game and down. Just don't shoot them a lot, and they will last a lifetime.
I have loaded for 4 .300NMIs now. Always with 230 Berger Hybs. Have seen them go as high as 3100fps, but accuracy nodes seem to be at 3000-3040. Brass life is good with Lapua. Barrel life, I have no clue. Haven't seen one shot out yet. Fire forming is a PITA. Usually takes 2 firings to fully form the brass, but after the first, you can start load development. A 245 should be able to reach 3000fps too, but you will have to lean on them harder. Recoil will show up in spades.
That being said, for a LR elk thumper, out to 1000+ yards, flip a coin. Both should crush if you can make the shot. Since you already have the correct action/bolt face, I would go .300NMI personally.