The Icon Pro is leaps and bounds better in every category over the Ultra series. The Icon Pro bag is a welcomed step up with 500 d cordura. The suspension and belt is a HUGE improvement over previous Icon/Ultra offerings. The most recent frame is solid.
I have not been a fan of KUIU packs ever since they came out. I have owned every generation of KUIU pack made and not been happy. That is until the ICON Pro. KUIU got it right with the Icon Pro. This pack is right up there with the Stone Glaciers/Exo's/ MR's and Kifaru's of the world at half the price.
And before you Kifaru guys jump all over me, I am still a HUGE Kifaru fan and prefer their packs over any. I'm just saying this Icon Pro is a valid player in the pack market at half the price of some of the biggies. If I could only own one pack, it would be a Kifaru, but this Icon Pro is a darn good pack for the price. The only thing I would change on the Icon Pro is the waist belt and buckles. If they "beefed" theirs up like Kifaru/MR/Stone Glacier, they would be a serious contender in the comfort category for me.
I used the Icon Pro 5200 on a Central Barren Caribou hunt this year and it performed flawlessly hauling 3 separate 100 lb. + loads of caribou. It handled 100+ about as well as could be expected with that kind of load.
IMO you cannot go wrong with an Icon Pro. If they'd come out with a 3000 ci bag, I'd be all over it.