No real difference performance wise to me. The 2014 allowed finer torso length adjustments but overall I prefer the 2015 harness attachment to the frame. I have packed multiple elk with each and really don't notice anything in particular.
Part of the reason I was looking at a 2015 frame was I need a medium belt to replace my large. Sounds like I may better better off just order a replacement medium belt. Thanks.
I have a 2014 and was recently put in a situation where we had to haul an entire elk out in 1 load. I put half an elk on it. The total weight was (not surprisingly) crushing after 4.5 miles, but felt surprisingly "good" when I first put it on and for the first 3 miles or so. I have a hard time imagining that another frame would have carried that weight any better. I did have to have the foam in my chest harness replaced as it was making some noise, otherwise, I'll probably be using the 2014 pack for the foreseeable future.
Thanks. I just put a 2015 bag on my 2014 frame and am pleased with the upgrade. I see no reason to upgrade the 2014 frame but may have to buy a medium belt.