Pockets380,
I think you just made your decision. 300rum. Shoot it and have fun till you don't like it any more then re-barrel into a 338 edge. That's why the edge is so nice.
I've had a Knight Extreme for a few years now and have had no problem taking deer every year. This last year I took a whitetail at 210 yards. I've been shooting Barnes 290gr TMZ under 100gr Triple 7 loose. I have been very happy with it and would still be using it this year except my wife...