I have an original ICON Bag and a 2012 frame. Have hauled out 4 elk and 2 deer with it, and totally love it. Twice I have carried out both front quarters and both backstraps in a single load, so that had to be close to 90#. My other comparisons are an Eberlestock J34 (1 Elk and 1 Deer). its been regulated to by daughters pack and an Alaskan Guide - 2 camping trips was all it took to regulate it to a backup.
Let me start by saying that their customer service is second to none - Hence the reason I have the newer frame. I have also spent some time on the phone with their guys on the fit of the bag. I'm a bigger guy - 6' 225#, so I don't have the waist belt issue, and it sticks in place very well even when packing meat. The shoulder straps are comfortable and do not leave your shoulders sore after packing heavy loads. Last year after 2.5 days of Rifle Elk season, I had packed out 2 elk, and over 23 miles of meat hauling round trips no shoulder soreness. I know that Aaron doesn't like the icon because of the load lifters. I haven't had much of a problem with mine. I can transfer the weight from hips to shoulders pretty easily through manipulating hip belt, shoulder straps and load "stabilizers'. Mostly I do this depending on the terrain I am walking through.
As for durability of the bag, its holding up well. No rips or tears in the material or seams. Zippers are still functioning as they should. Same with all the straps and buckles. I have used the pack pretty heavily during hunting season - The remainder of the time, its stuffed with a 40# bag of salt and I walk probably 15 miles per week with it. So the straps and fabric gets a pretty good workout.
Best of all, I love the organization capabilities of the bag. There are a lot of nice little pockets in the pack and the lid for putting your stuff without the need for external pockets. The pockets, combined with the horseshoe opening lets you get into those pockets without having to open the entire bag and remove its contents to find what your looking for.
Compresability is great as well. I use mine as a daypack, summertime family camping or scouting and when I am backpack hunting. So it can have 10#, 50#, or 100# in it and it is able to be strapped and secured just fine.
As for me - the Kuiu ICON is my pack - I know others don't like it, but it works for me just fine.