I think it was about 6 years ago, I called Greenhorn on my way through Montana and asked him about packs. Without hesitation he told me to stop on my way through Bozeman and look at Mystery Ranch.
I was pretty sure at that time, that internal frame packs sucked and that the only thing to use was an external.
I stopped on my through Bozeman and looked them over, tried a few on and when I was in the store the crew cab had just come out. On my way back I stopped and bought a NICE frame with 2 bags, the 6500 and also a smaller one they called a penguin. I used the smaller bag for about a year at work then got a second NICE frame with a crewcab. I've used it for I believe the last 5 years. Its the pack I use the most...by far.
As to the durability of the crew cab and NICE frame...pretty darn good. I sat down and tried to figure out just how much I use the crew cab every year. I typically work in the woods 8 days each 2-week pay period and work in the field for 18-20 PP's a year. So, thats 140-160 days a year. I'd say in any year I probably hunt 30-45. I usally do bit of antler hunting and some misc. hiking for another 8-10 days a year. Basically, I'd say I wear my pack near 200 days a year give or take.
Its also fair to note that I've had my pack rolled on by a horse several times in the Frank Church...came real close to killing the horse. I've had the pack stuffed into the back of airplanes, strapped to a motorcylce last year a bunch, bouncing around in the back of the truck, atv's, etc.
I wouldnt say I'm extremely tough on that pack...but its a long way from being pampered either.
This is my pack that I took some pictures of about 5 minutes ago in the back yard...going on year 5 and by the years end I'll have over 1,000 days of use on this thing.
I've not had a single buckle failure, not a single strap break, no zipper problems, nothing.
The ONLY thing I can see any wear on at all is right at the top of the straps on the flex point...you'll see it in this picture:
I was burning through 1-2 new backpacks every year at work...this thing has 4 tough field seasons on it, plus all the hunting, etc.
I dont know of any other pack that would still be in this kind of condition after that much use/abuse.
I usually dont recommend many products, but I believe the packs I've bought from Mystery Ranch are worth bragging about. Its just a great product with an unbelievable warranty and the customer service I've received has been top notch.
The only regret I have is not owning them sooner...