Here's my take on it. You didn't ask about Kimber Montanas, but a Montana in .308 is what I'd be looking at, and it's still a little lighter than an Ascent in '06. I've owned a few Montanas and handled an Ascent. I just didn't like the feel of the Ascent, plus you're stuck with a muzzle brake if you get one. The Montana just felt more solid, and as far as the trade-off between light weight for carrying vs. more recoil, 5 lbs. and change for a .308 is about my cut-off. I just don't see a need to go lighter than that, especially with a chambering that'll have more recoil than a .308. It just gets to the point where it's bordering on unpleasant to shoot much at the range.
I'd go Montana in .308 (or 7-08), for the following reasons:
1) Looking at the MSRP, you can get a new Montana, shoot out the barrel or just decide to have it re-barreled with a premium after-market barrel and pay the same as an Ascent.
2) I hate loudeners and lengtheners (muzzle brakes).
3) You already have a lightweight 300 WSM, a lightweight '06 doesn't get you much that's different.
4) For practical hunting purposes, a .308 will do what the '06 will.
PS, if you've made up your mind on the Ascent and are worried about ammo availability, get a .270.
