I think Trailrunner has it--you're going to have to experiment to see if a VBL works for you. It does for me, but obviously not for everyone--we're all different!

A few one-night trips into frigid areas would be a good test--preferably close enough to your car that you can bail out if things go awry. I normally recommend the back yard (if you have one) as the ultimate gear testing location, but in your case, as in mine, it usually doesn't get cold enough!
May your trails be crooked, winding, lonesome, dangerous, leading to the most amazing view--E. Abbey