Any reason whyBig Agnes bags are not a good design?

Read: 2006 Unconventional Sleep Systems Manifesto
http://www.backpackinglight.com/cgi-bin/backpackinglight/2006_unconventional_sleep_systems_manifesto.html

The top bag idea itself can have merit. Big Agnes fails though, in my mind. The point is to save weight, but their bags are huge and heavy. The top bag takes some getting used to… some people love 'em. I personally find it easier to sleep and roll about in a normal bag. Also have found that while I can curl up in a snug-fitting mummy and the bag just curls with me, that can't happen when it's strapped to a sleeping bag.

It really comes down to what a person likes. I prefer room in my bag and gained a little weight so I could move around. Before that I slept in a tight fitting bag. I still use that bag – for summer trips where I lay the bag over me as a quilt. For colder trips though, the BA bag is my bag.

One reason I am willing to carry a bit more weight:
With the BA bag I am able to toss and turn – the bag and the pad stay there, not moving. Only I move. With a narrow mummy bag, when I toss, my back gets exposed – flattened down – and get cold spots.

Since bumping up to a BA bag I sleep warmer and more comfy.

I have owned five of their bags over the past six years. The semi-mummy style bags (that take a rectangular pad) I found to be very comfortable. But as I started my transition to lighter weight and smaller packs I found them to be too bulky as they used 650 fill down, and of course too heavy.

Last fall I bought two of the new SL bags as I really liked the 800 fill down and the weights they were coming in at. They packed down very small. These are true mummy bags and use a mummy-shaped pad.

What I found being a side-sleeper was that I was not comfortable in the lighter bags. As one was a 0 F rated bag I needed to have the hood closed when it got very cold and it did not work well to turn over. Half my face was in the bag. The 20 F bag is a little better as I rarely need to be completely closed up at those temps, I can wear a hat and keep the hood looser.

As far as the pad being the insulation this has worked well in my experience. I use a Dual Core on snow with the Pomer Hoit 0 F bag, and either it or an Insulated Air Core with the Zirkel 20 F bag depending on where I am. In fact at Mt Langley with a Yampa bag on an IAC the pad kept me warmer than the bag did.