I have had the J34 and the Icon Pro and the x2. Don't get the x2 if you are over about 5'6". I am 5'10 and it is way too short. you can never support your load with the hip belt and after a week, my shoulders were dead. I never did much with the j34. It was nice, but at the time I felt it was too big for what I was doing. I have the Icon now, not the pro. and loved it during this years hunt. The suspension is phenomenal, and the power pull (like the osprey packs) waist is phenomenal. you can cinch it down like nobody's business. I has the 1850 bag, but bought a discounted 5200 after xmas. Funny, now I don't feel that is too much space. BTW...the J34 has stays, not a full frame. The icon series is a full carbon fiber external frame pack. I have seen used ones for around $200 with the 1850 ci bag. bigger bags command more money. Don't get the 1st generation. I have the last one before the pro, and I think the frames are a touch better in response to the issue with the bottom stays breaking.