Back to the OP's question... I doubt there's one answer that fits everybody, and this is conjecture and extrapolation on my part, but I've got high hopes that my Kimber 8400, currently a great 7 WSM, will be even better as a mid- to long-range mountain backpack rifle as a 6.5 SAUM. "Same" ballistics in the ways that matter and a nice step down in recoil. Now that I own the reamer, I suspect that'll happen down the road. I just chambered the rifle I bought it for- a little heavier build than a Mountain Rifle or Kimber- this weekend... pretty excited to play with it this spring.
I'll throw out there that a mere mortal might could even stand to buck up and carry a rifle a bit heavier than the Kimbers and Mountains of the world.... if he's truly intending it for mid to long range. Just a little extra heft goes a long ways when it comes to repeatable precision shooting. And for the love of all that is Holy, set that trigger crisp and LIGHT and don't look back!
