In reply to RBK:
This is really hard to answer as I haven't tried them in Scotland yet. However I had a couple of weeks in them in Europe, some days very cold in the Dolomites. I though they were warmer than any other boot I've owned (Nepals, Trango Ice, Trango Tower and Cube's). I've always had cold feet whilst climbing, even with my Spantiks, for me it's then how to manage to get the blood back in at belays. I found with the G-techs the moment you get to the belay and release the BOA my feet were toasty as in a few minutes. I think the high gaiter also adds a lot of warmth too. I own a pair of Lenz heated socks which I use with the Cubes, which I had with me but I didn't need to use. So they actually rank at the top for me, for now anyways. But as said, I only had about 12 days climbing in them, so not enough. But I absolutely love them.