Thank you for that article.
It's interesting to compare this to Mike Clelland's description of how he fares on month long outings at sub-zero F temps. I'm not familiar with Michigan or the Rockies, and I wonder if one system is more appropriate for a particular location. Where I am in the PNW in deep winter, I don't feel any need for VBL while on the move (other than socks), but it really works for me when stopped (esp. the featherlite mitts, but not vbl socks - need to air the feet out until I get in the VBL bag).
Unfortunately, it sounds like a wool baselayer does not work as well as synthetic when used in VBLs. I've just discovered merino wool baselayers, and they smell much less worse after a week in them. But they seem to get wet in my VBL, whereas my polypro never did. If anyone knows how to make wool work in a VBL, please let me know any techniques.
Finally, in addition to the manufacturers noted, Feathered Friends makes (made?) a nice VBL bag with a half zip, with snaps to link to an FF sleeping bag.