+1 on the Terramar silk liners!! I love them, in fact when the fingers finally wore out of my first pr, I just cut the tips off, great for cool morning hiking. I buy them 2 pr at a time. I had a pair of them under a pair of smart wool liners and was very comfortable, taking them off as soon as my hands warmed up.
I actually took a pair of the hand warmers out with me when I ran out of the toe ones, but didn't end up using them, since it was just a couple of toes on one foot cold.
One thing I discovered last night after reading a post on BPL, is that the warmers have expiration dates...didn't know that , checked and mine were out of date (I'd had them a good while) which could explain their half life. I'm going to test some new ones. I like the hot water bottle idea, and for car/canoe camping, or emergency, I'd use it, but it takes fuel and water=weight, so I hope the warmers will work.
Another thing I overlooked was a pair of sock liners I used to use for skiing, they are by far the loosest fitting socks, and under my loose fitting,fuzzy, thick smart wool socks,which I only wear to bed, they likely would have performed better than the two wool socks I ended up using, as after checking the top of the inner pr was a little restricting. And, when changing socks, I didn't let my feet completely warm before going back outside....easier to stay warm than to re-warm business and all
I did learn a lot from the test, and have even greater respect for my gear now as well.