Barry makes some good points. In addition, the Kifaru bags have huge interior dimensions, apparently to allow the user to sleep fully clothed including boots, if necessary. This concerns me with respect to the temperature ratings for a typical backpacker, since in my experience a snug bag is warmer than a roomy bag, all other factors being equal.

If you factor that in, I am sure they are extremely good quality wise. For layering with puffy synthetic clothes or a down liner bag they would be very good.