I have owned eight packs over the years, shown in the pictures below. The second picture is from 1973, camping at a trail head at Big Bend National Park. It shows my first three packs in use, as I was loaning two of them out for the trip, plus my current one at the time (#1). The third picture is the Elemental Horizons Kalais.
-1. Canvas Boy Scout Pack on aluminum frame ’69-’71
0. REI pack on Camp Trails frame ’71-’73
1. North Face Panel Loader Pack Bag on Kelty Frame ’73-’92 (33 trips), 80 oz., ~4500-5000 cu.in.
2. Mountainsmith Elite 4000 Panel/Top Loader ’92-’02 (20 trips), 104 oz. total (116 before trimming), 5000-6000,cu.in.
3. Mountainsmith Auspex Top Loader ’02-’05 (15 trips), 59.5 oz., 4200 cu.in.
4. Six Moons Designs Starlite ’05- (21 trips), 28 oz. w/stays, 4200 cu.in.
5. Six Moons Designs Swift ’10- (9 trips), 17 oz., 3500 cu.in.
6. Elemental Horizons Kalais ’13- (14 trips so far), 35 oz., 3300 cu.in.
Now the side views:
Obviously as the equipment gets smaller and lighter so does the pack you need to carry it all with. Many folks suggest that you work on reducing/changing your other pieces of gear first and then finally get a pack that is the right size and support to carry your new load. You can see that with each new pack, from #2 to #5, I have reduced the weight of just the pack itself by almost half each time, that is hard to achieve with almost any piece of gear you change. The newest, the Kalais, is a reversal of that weight loss progression. Like many people who get down to very light packs, I have decided I wanted a bit more load carrying capability, especially for the desert trips, so I have added some weight back to my base weight to accomplish that.
Packs 3-5 were the transition to smaller, lighter loads. The Auspex is a killer load carrier, you could probably carry 60 pounds with it and be comfortable, it was one of the first sub 4 pound packs but Mountainsmith no longer makes this model. I used it on the walk across the eastern half of Big Bend and started with 47 pounds and was very comfortable. I have mostly used it without the top pocket to save weight and didn’t need the volume.
The Starlite has optional stays that I think make it work better, especially with the load lifters. Mostly it, and the Swift, relys on your sleeping pad in a special pad pocket as the frame, a closed cell pad works best. (As of fall 2013 both the Starlite and Swift are no longer available as SMD is releasing new designs) I used the Starlite on the walk across the western half of Big Bend when we had to start with 40 pounds and that is the limit of comfort as far as I am concerned. In training walks I had up to 50 pounds in it and would not want to carry that much all day long!
The Swift is very comfortable with loads under 25 pounds especially considering it does not have load lifters or a padded hip belt. I started out the week long Upper Paria River canyon loop with just under 30# and it carried beautifully but that is about it’s comfort limit. Amazing for a 17 oz. pack!
The newest pack, the Elemental Horizons Kalais, is the result of not only 40 years of carrying packs but a years worth of in depth research you can read about the Search for the Perfect Pack here. So far but it seems to be as comfortable as discussed even up to 40 pounds.