Yes, I think they're great too.
I still have to get in touch with them. I just asked by email whether it would work without the inner jacket.
In terms of weight, I'm not so sure whether it's really that heavy. I don't think the chamois-tanned leather is necessarily heavy (but not light either ;-))
I came across this tannery from an Instagram account that makes newsboy caps from this leather. Also very cool. But I'm not sure if that's not overkill in combination with leather jackets.
Good point about shedding the inner jacket. I am not a fan of zip-out liners and rather layer with a thick jumper or hoodie. Reduces the bulk of the jacket to.
Chamois tanned deer is really special. I love how it ages and gets darker with wear. Incredible stuff! I recently lost 5kg, and now my old Meindl "Lederhosen" fit perfectly again!