I've been using the Initial Ascent 4k a bunch for scouting, taken it backpack bear hunting, also packed a fair sized bone in elk a ways in it. So I'm going to do like a mid way though the review thoughts right now.
Ok here a few things that aren't my favorite about the 4k.
The single zipper on the lid. Makes getting stuff in and out when it's full a pain without everything spilling out.
I also don't like that the lid straps didn't have a keeper to roll them up. I found myself pulling on them when I wanted to tension the load lifter straps simply because they were longer. I mentioned this to Dennis and he hooked up with two more keepers to resolve this. Thank you
Lastly I imagine this effects very few users but I personally have a long torso. When using the shoulder harness my upper portion surpassed the locking Velcro and allowed the very top part to slightly shift when shouldering heavy loads.
Here's a picture of a more average harness and where it sits on the frame vs where my harness sits.
I again reached out to Initial Ascent and they happily added some Velcro higher on my frame. Here's a picture of the standard Velcro layout
And what was added to my frame.
Seems to have resolved my issue.