I have now worn this on its own and under a helmet. I have worn it in rain, snow, hail and with the frost forming around me and have never been less than impressed with its performance. Very thin and with flattened seams it was ideal for wearing under my helmet on those colder stags.
Held up to the light you can easily see through the material but I have never been cold in it. I have never been hot either though. My head has been kept at a reasonably comfortable temperature the whole time; it feels a little strange at times as though there is no hat there at all. I could feel the wind through the material but it was not cold, like I said very strange.
I wore this hat all weak on ex and had it in my pocket when not on my head; it was wet most of the time. Even putting it on my head damp did not take away from its thermal properties and it dried incredibly quickly. There was remarkably little odour to it at the end of the exercise, even after the rough treatment it had had. It has also held its shape and after a wash looks like new again.
Now this is all subjective, as while I who, while not exactly follicly challenged is lacking a decent cover on top of the skull, I do feel the wind and cold more than the missus who has, what is only second to a 13.5 tog winter duvet and fetching blanket on top of her head. So what feels cool and comfortable to me may be hot and sweaty to someone like her.
Now for the price. I do think that this hat is priced competitively; I have never paid more than a tenner for a woolly hat before and would always begrudge paying that. However if I wanted to replace this I would cough up for another (or get someone to buy it for a present).
The Armadillo Kojak was kindly provided by Armadillo Merino.