I got one about 3 years ago as a warm layer for when not skiing on a Norway trip. Layered up because it was just a pottering around warm layer then. I had plans to use it I winter dog walking and hiking. I only used it as intended when hiking.
I also tried it out in very heavy rain on my local dog walk route. That time over bare skin. It was amazing. This was raining stair rods. I got the hood after that. You must get the hood too! Otherwise rain down the neck. That was the only route the for the rain to get in over an hour in that rain. Amazing as even my best wet weather gear would have been uncomfortable in that. Water wicks up the sleeve and sweat dampens you out with hardshells, even paramo too!
IMHO wear without base layer if working hard n in the cold. If less strenuous i do not think it's warm enough. I don't feel the cold often but I remember a cool wind feeling like it was blowing through the zip area.
I'm not a fan of wool base layers and I can only think they'd mess with the pile capillary effect. I've read that the only layers to potentially work is big wicking synthetics. Polypropylene for example as it wicks a few hundred times better than nylon or polyester. Wool doesn't wick so much at absorb and lock away water.
Wrt layering underneath, buffalo say bare skin but montane says base layer. Montane is warmer than buffalo s6 shirt. I say synthetic base layer unless you're exerting yourself or the weather is not good. Then it is better next to skin.
BTW it's comfortable when wet. In know a guy who did the Yorkshire Dale's the peaks twice in less yuan 24 hours in mid winter for fun! He did it with just a buffalo Mountain shirt. He was out in a bad blizzard and very cold temperatures including 2 or 3am when it was -10C inside the building which had been heated until about midnight. A very hard frost indeed. He was the only one not cold but he was fair shifting and hardly stopping.
Did I say get the hood? When cold it's very snug wearing it and it is good to stop rain down the neckl oh and make sure it's as close to your measured chest size too. It needs to be as close fitting as possible to wheel.
thnks that’s really useful, I will get the good to!
baselayers I have bamboo, and wool (merino) so will experiment with those - and look into polypropylene ones aswell