Thanks for creating this thread, Piper, and to those who have posted here.
When I go on camping trips with some family members, they often bring their Mountainsmith Tour lumbar packs with them for use as day packs. I would normally leave stuff at base camp, empty out my ULA pack, and use that instead – oh so lightweight-minded. :P
But, for not wanting to dual use a smaller backpack as a stuffsack/daypack, and not really-liking the minimalist lumbar packs, I’d end up carrying around my backpack everywhere I went. I get some pretty serious sweaty back, and watching my family members jump around with their little butt sacks, I decided I wanted in, too (Thank you REI 20% seasonal discount.)
Now I can stuff a Nalgene bottle in one-side water pouch, my Jetboil in the other side, and some noodles, a bivy, and other trinkets in the main sack. I have not been able to do an overnighter with this set up, because it seems darn uncomfortable, but I am getting tougher. :)
I think I would add a Neo-Air mattress, and a lightweight down jacket for pseudoquilt or as a pillow. If I need to bring so much stuff that my lumbar pack warrants using shoulder straps, then I see little reason not to upgrade to a higher volume, and much lighter backpack.
I do really like the ruggedness of the lumbar pack. It is nice not having to be careful with it. Thanks for causing me to think about using it as my exclusive carry gear for some short adventures! Thanks, Piper.