It seems there are a few token posters on other forums about SS but the replies are always fanboy and brief. Have heard it lacks flexibility and wonder a lot on weight. The idea of wearing this stuff over just a single under layer into the 20s fascinates me... but I’m getting longer in the tooth and know things that seem to be too good to be true......
I've used aerogel at work for high temperature insulation and in static applications it's performance is unreal. However, it isn't very flexible and the industrial stuff is super dusty. I would be skeptical of its use in flexible fabric applications.