I used the VBL system off & on for over 2 years. The temps were from 0°F to 40°F. I have tried the full VBL mummy sleeping bag liner (6ozs), and VBL Clothing (@ 18ozs). Like most systems, there are pro’s and con’s to the above.
Needless to say, the VBL bag liner covers you head to toe. I would wear Wal-Mart silk tights, shirt, and silk socks. They’re almost the same as Underarmor. It just feels better getting into & sleeping in them in the liner. If they get wet, they dry fast. However, getting into them is the same hassle as a regular bag. However, it’s not like I have anything important going on when I get in the hammock, so a few minutes, with lifting, twisting helps warm you up as well.
A few times, I woke up cold, swimming in my sweat inside my liner. My thoughts on the reasons were, I ate late, I didn’t wake up, I didn’t vent and I ran out of fuel inside my core which produces the heat to keep me warm.
I’m a male, so a pee bottle is my best friend when I hike. So once I’m in, I’m in. The only reason I’ll exit my hammock at night is for falling trees and amorous bears who heard me fart and thought it was a mating call.
VBL clothes for me, work great. I wear the same silk tights & shirt. I have a Stephenson's Warmlite VB Shirt, Gram Weenie Silnylon Rain / Vapor Barrier Pants, VBL Socks, & use a plastic bag on the top of my head with a Balaclava. The Warmlite VB shirt has a full zipper, which makes it very simple to vent. I wear over these, a middle layer Polyester pants & shirt and down booties.
The above system allows you to sit around a camp fire, do chores, etc…
There is a ton of new technology coming out all the time. And while I think the VBL sleeping liner, is the lightest, less expensive, and the most effective for me, I’m always looking for the next best & the greatest to come along.