I used a MR Longbow (and crew cab and metcalf) exclusively from 2011 until about Jan 2014. A buddy of mine owned a 2013 KUIU Icon 1850 that he'd used the entire 2013 season. Right before January 2014 archery javelina and deer season I sold my crew cab bag and bought a 2013 icon after seeing how well my buddies pack performed(and how light it was) . I used that on most of my 2014 hunts, Jan 2014-July 2015. This past July (2015), I upgraded to the 3200 Icon Pro. (I like the 3200 more for a general purpose size bag). The only hunt I didn't use my 1850 on in the year and a half I owned it was on my southern az coues deer hunt. I used my metcalf on that coues hunt for 2 reasons; mainly pack bag size and secondly overall durability.
I carried my icon 1850 on my 2014 archery javelina and deer (packed out my javelina), spring/summer archery bear hunt (packed out a portion of my bear), aug/sept archery deer, a buddy's archery elk hunt, a buddy's bull elk hunt (packed out portion of his bull), a buddy's daughter's cow elk hunt (packed out part of her cow), my wife's cow elk hunt (got the truck to the cow elk, so no pack out), my buddy's coues deer hunt (packed out some of his coues), 2015 archery javelina and deer, a buddy's spring buffalo hunt, and another buddy's archery spring bear hunt.
I've still been regularly using my icon 1850 for training hikes on weekends with loads of ~40 lbs.
I haven't gotten rid of my MR Longbow and Metcalf packs, but they don't get used near as much. The biggest thing for me is the pack weight loss of using the KUIU packs. I drop about 4 lbs off my pack weight when switching from my longbow to the 1850 (now 3200). For carrying around all day, on multiple trips, the weight loss is noticed.
I really like the Longbow bag layout, I feel like it was designed just for me, but carrying a 7+ lb bag all day takes its toll over multiple days.
I've read several posts and seen pictures of broken kuiu frames, but so far my 1850 frame has held up well, and I expect the same from my icon pro 3200 frame. I'm not one who babies or takes it easy on gear.
As far as packouts, I haven't had the opportunity (or need) to pack out super heavy loads in my 1850. I've carried elk quarters and other (pieces) of animals, and it has performed well. For a first load out pack, it has done great. Even when used with multiple loads.
I've used my MR pack on a lot more packouts, and have carried heavier weights. (Heaviest confirmed/weighed load was my wife's 2012 bull where I had 90 lbs of meat in the longbow bag and also sandwiched between the frame and bag (front and rear quarter, bone in). It has always rode well, especially after the lift kit was added to the NICE frame.
I would say that I feel the MR pack is more capable of heavy loads and more comfortable, but the Icon performs very well for being a lighter weight pack.
In regards to needing an actual meat shelf, I normally carry bone in (elk) quarters, but the times I've carried loose meat in between frame and bag on my MR pack, the straps have been fine.
Not that this was asked, but the only MR pack bag I've tried I couldn't get to work well for me was the crew cab. It seemed a jack of all, master of none bag. I found I prefer a more traditional pack bag, and also the weight was carried too low on the crew cab. The lift kit helped some, but for the times I wanted to use the crew cab, it seemed way too heavy. I bought the icon 1850 to basically replace my crew cab use. Oh, I did rig the meat shelf on the 1850 to ride higher than originally placed also to help lift the load up higher.
Hope this helps some and wasn't too much info...
