Those are two of my favorite actions, right after a Win pre '64 M70. I own several of each and like the Model Seven much more than the M700 (even in S/A form). Of the two calibers you've mentioned, I think I'd choose the .308 over the .270 caliber feeling (as already mentioned) it loses less from the 20" barrel than the .270. I feel the .308 and a 20" barrel is actually a great combination. If you're liking the all-weather properties of the Model Seven, then go with it, by all means. One of my model Sevens is actually a 673 in .308 and it is a fine shooter. That 673/.308 wears a nice Leupold scope, a Leupold European 30mm 2-7x33 and it's a very fine mate to the rifle and caliber, IMO.