If I were to go long action, I would go with a 280 or a 280AI over the 6.5-06.
I once had a Rem M700 KS Mtn Rifle in 280 Rem it did a great job with Nosler 140gr BTís. I worked up some loads with the Sierra 160gr SBT, they shot very well too, I never killed anything with that load.
My experience is only with the 6.5-06. My hunting partner has an improved version. I would not get the improved version. I don't think you gain enough in this chambering to make it worth while. jmo. I have thought about a 260AI for my self. I think it would be a great round, but I think I like the little extra punch that the '06 offers.
For what it's worth, I think the 6.5 cal is a fantastic killer, 130 to 140 grain bullets. I have seen two elk down with my son's 6.5-06 using 130g Scirrocos. One at 375yrds and this year at 310yrds. They work well.
im not a suscriber to the 1 size fits all mentality. id prefer several rifles.
but in your case id pick the one that would do the best job on the largest animal you will be shooting at.
recoil, barrel life, etc. should be of less concern.
Location: The rifle range, or archery range or behind the computer in Alaska
Re: 260 Rem Vs. 6.5-06
I voted for the 260.
IMHO the longer action, added powder, less efficient design, shorter barrel life, added recoil and so on doesnt seem to justify the small increase in performance. Heck if you go with a long action and burn more powder, dont joke around and go bigger. Dont jump to a LA for a small increase in performance. Longer rifle, heavier rifle, longer bolt through etc....These are OK if the gain is more than 100-200 FPS. The game wont know the difference. If youre really concerned about a bit more then use a 26" barrel and VV N500 series 'high energy' powder. You will make up that 100-200 FPS in a hurry.