Thanks for your comments and the link to Andrew's article on the subject of VB. Andrew spoke from his own experience and that is the proof of the pudding, as they say. I don't think science of VB is yet understood. In some cases it works and in others not, for some people it works and for others not. Why the discrepancies? Because there are too many random variables. Part of the fun of backpacking is experimenting of course. Skurka has certainly done a lot of that.