In reply to An Triubhas:
I have the ultras (very similar) and they're brilliant. Even in the coldest wettest weather Scotland can throw at it they're super toasty. Plus they are very waterproof and the integral gaiter is a godsend and one less thing to carry.
Unlike other boots I've used, they don't seem to freeze solid so even in minus 20 they don't need to be left in your sleeping bag... they slip on well and warm up quickly.
Given the difference of a hundred and something quid over a pair of Mantas say, I think they are worth the cost even if only for Scotland. Hands can be warmed up in your jacket but cold feet are a disaster so why risk.