I own the Jam and honestly, of the 8 packs I own or have owned, it's my favorite. Durability was a bit of an issue for me and so far it's shown no signs of wear even in the brush and on the rocks where people report shredding the silnylon packs from golite. I don't feel the need to baby it at all. It's very comfortable, a soft pack conforms to your back in a way that no frame pack I've ever carried does. It almost feels more like wearing a vest than carying a pack. Up to 25 pounds it's the most comfortable pack I've worn.
I also like the feature set, as it can carry all of the tools that I want to carry (ice axe, instep crampons, poles, snow claw, snowshoes) and it is just the right size for 1-4 night trips. But if you think you might need to carry more than 25lb much the infinity would be better. The unlimited suspension is impressive if you need the load hauling ability, but extra weight if you don't. And the durability issue depends on what you are going to do with it.