I have an OK Guide Frame plus an original which to me is exactly the same as the Gen. II. I have a Crew Cab plus Bivalve lid on the OK and a 6500 bag with a pair of Longpockets on the original, both with pairs of Fliptop Pockets and Kifaru Gunbearers.
These are the BEST packs that I have EVER used, so superior to anything else I have tried that comparision is meaningless. I have hauled 90 weighed lbs. on the original in comfort and am working up to heavy loads with the new OK....just fabulous packs, IF they FIT you.
Now, if you do not have a 44" or larger chest, I think that the OK might be a bit too much of a good thing, although they do have a medium yoke for it. Also, unless you regularly backpack elk, Moose or other such heavy loads, you are better off with the Gen. II. The Gen. II is, IMHO., the absolute BOMB for a general hunting pack, especially with a 5000 bag plus a Crew Cab for shorter trips.