If you are just looking to cut weight, then generally rifles are the most expensive place to find weight savings. I played the lightweight factory game for a few years with Kimbers and Sako/Tikka. But settled on a couple of full custom rifles. I just preferred the fit/finish and ergonomics, over the factory rifles. While the accuracy is definitely better, it is the consistency of that accuracy that is more important to me. A rifle that fits is going to shoot better in a wider range of conditions and positions. So whatever model you look at, I would stress the importance of finding something that fits you well.
I'll 2nd the above comments that 280ai should really be looked at as the minimum mountain cartridge. 7saum is a ballistic twin and is what I've built. I have shot a bunch of bears in the past number of years with 6.5's ranging from 260rem to a 6.5ss (short Magnum wildcat) and I was less then impressed with the results. Step up even to a 7-08 and there was a noticeable improvement. The size of the hole really does make a difference and for me 7mm is the minimum now.