Fairly thick, I'd imagine about the same as the one you just picked up. And yeah, it's a cool idea, but true ballers/nerds only - the fact that it's non-removable kind of kills the jacket for a lot of casual wear. I wear my Stooges with a Patagonia down vest all the time, bit more versatile
you fit this down vest under a stooges? interesting! I assume this is super warm during the winter.
Do you mostly wear RO leathers? I remember you have an incarnation but haven't heard much about it.