My buddy is looking for one and trying to decide the same thing. Losing your ammo is a really a non-issue. Put a couple of boxes in the hard case and IF you have your rifle, you have your ammo. My biggest concern with them is how fragile they are. A barrel that thin is not very strong and you would have to be careful with it. Although there isn't a lot of difference in these chamberings, if you can handle the recoil, the 280AI is certainly the Thoroughbred of the bunch. My lightest rifle is a 700 Mtn rifle in 260AI. It is a joy to hunt with and quite accurate but not as easy to shoot as my much heavier 6.5-284. Strapping a rifle on your back makes the weight savings a moot point, hanging onto it in rough country makes a huge difference.
Myself, I would get a Montana but since you want an ascent, I would suggest the 280AI. As reported, you can always shoot factory 280 ammo in it but you will lose about 100 fps fireforming.
