Yes, we also fold our home-sewn liner down which is the main benefit. Previously we used reflectix, which I think was a better insulator. However, our implementation was not as good as we only had self-adhesive pads of velcro and there were gaps. The custom liner we have sewn is using a much better looking material (Evolution), but it is thinner. The air film and captured air layer are it's main insulating qualities, otherwise it's a two ply breathable fabric without any appreciable R value.
If I was spending nights in 3F or colder I would want more. We've considered slipping sections (4' long) of our old reflectix between the new liner and outer wall, especially above the head of the bed. Those could be removed and stowed during the day. Our system is velcro panels with window flaps, so it would be possible. This is untested and only a concept presently.
If you're into insulation, you may want to consider adding some closed cell foam pad, 1/4"thick, to the front lift panel surface. We're thinking of cutting up a yoga pad for this. I currently toss my down parka between us and the chilly lift panel. But again, I camp in California / Nevada with mild temps in the teens and twenties. Apologies for all the imperial / ferinheight terminology, I hope you can translate to metric / celsius better than I.
