"Wear it for 10 miles and then report back."
Uh, OK.

Works fine. The bulky load above is the shelter and what-not for my wife and I, as well as all the food and cooking gear for us and two nephews for an easy weekend trip. It was an easy 6 mile hike in to a lake that day, but maybe a 12 mile hike out over a rugged little 4,100 foot mountain the next day. I guess that meets the 10 mile minimum for the report? .

The wife likes her Jam 70 as well.
She carries all our bedding which is a bulky but light load. I reckon her pack was about 14 pounds that day.
Only reason I got the 70 liter Jams was because they were on sale at quite a discount. No bloody way I could have otherwise afforded new packs for both my wife and I, and I'm glad I got the 70 liter versions.
My wife uses the pack every week to carry dirty laundry down our mountain so she can go to a Laundromat in town to do the washing and goof off a little as well. It's her once a week trip off our mountain. She always did insist that she would not wash our clothes in the sink as our one neighbor on this mountain does, and in the winter we have to leave our cars some distance away and snow shoe down.
The Jam 70 is perfect for this, and she is getting allot more miles under it than I am under mine!
I like the packs quite a bit. The price is right, and they are easily modified. I am thinking about removing the padding so I can simply use my sleeping pad back there, but as of yet I’m still in a state of flux on pads so I’m holding off on that.
I considered removing the hip belt, but having hiked a few miles with the belt dangling loose I have decided it really does help. My wife loves the little pockets on the hip belt.
I’m pretty sure I will cut the load lifter strap off. I can’t see that they do anything and they always get in the way for me.
I might ax the little strap in front ( with a whistle built into the buckle! ) that connects the two shoulder straps. Not sure if that is doing anything for me yet.
Were those ice ax loops up on the back of the pack by the top of the zippered pocket? They are already gone from my pack.
The compression system is great, even the odd tiny clips on the bottom to squeeze it together.
The runner up was the G.G. G4.
This was more expensive and I’m not sure about the removable hip belt. All in all I bet the Jam carries a heavier load with greater comfort than the G4, but then never having used a G4 I guess I’m guessing at that!
All things considered getting our first UL packs was quite a leap of faith because I couldn’t try the silly things on first!
All things considered I we think did good with the Jam packs, and expect my wife and I to be using them for quite some time, possibly even for an AT thru hike next summer.