Those packs looks great, if a little pricey. Can you comment on the padding on the hip belt and shoulder straps? It looks minimal, but OK for 7 kg loads.
I agree with much of what David wrote about the Hyperlite backpack. Most folks will find them a good workhorse.
These backpacks are designed for ultralight backpacking where normal load weights for extended backpacking trips normally would be from under 15 pounds up to around 25 pounds. So for 15 pound loads, it should be fine. However, it is hard to quantify what someone will find comfortable.
When I gear tested two of the HMG packs, including the 2400 series, I found them to be competent. They never really drew my focus of attention to themselves when I was backpacking, which is how I judge the wearability of a backpack.
If the pack takes me out of my thoughts - - which sort of just wander and flit around while walking - - and I am finding myself thinking about how to adjust the pack to overcome some niggling issue of comfort or pressure points, etc to make the backpack feel better, then it is NOT a backpack that I want to keep. Keep in mind, that this is different than the normal thing of doing slight adjustments to hipbelts and shoulder harnesses while walking. All packs will be adjusted in tiny increments on the fly as pack loads settle a bit, or tension of the straps is used to shift from shoulder straps to hipbelt or visa versa.
My experience in it over the course of a summer and 600+ miles in the Cascades and Rockies, is not so much that the HMGs are uncomfortable, but that it has a lot less padding than many of the backpacks I've gear tested for manufacturers or have used for myself.
The areas that might be more noticeable for some are in the hip belt, shoulder straps, and back panel. It also seemed that as I used it over the course of a few weeks, it seemed to "break in" and became more comfortable. Or maybe I just got used to its 'personality'.
My assessment would be that if someone is looking for a well cushioned backpack, this might not feel as good as some of the mid-weight backpacks like the Osprey's.
I really liked the HMG backpacks, including the 2400 series. They can be counted on, as long as there are not tiny holes in the material, to stay water tight in rain. The seams are sealed and the Cuben Fiber composite materials are waterproof.
That said, there are backpacks which are much less expensive, under 2 pounds, and also fairly water tight against weather which work just as well and that I also find comfortable. There are some backpacks which I find more comfortable than the HMG, too.
Bottom line from my perspective: if you are interested in the HMG packs, they are likely to not disappoint, but I would definitely make sure that you have ample time to test it out with wearing it under load.
