questions re: synthetic insulation in a pad

They do cost a pretty penny, but how long to you want to actively use it? 10 years? 20? Forever?

I'd say that "in general", any synthetic insulation will decay over time, no matter what. I would also assume that the closed celled foams would have a much longer decay rate than the open celled foams, and they would both probably take a lot longer time to decay than typical synthetic insulation.

By how much? I dunno… 1 to 2 percent per year would be my w.a.g.

There are some abstracts on the internet about all of this, and I suspect others on BPL may have looked into this before.

I would especially guess that a Synmat would probably get worse more quickly, since it is a Microfiber type insulation. While it seems more durable than what would be found in a sleeping bag, it isn't as stable as rigid or closed-celled foam insulation. Of course, if you never kept it rolled up, it might help with it's longevity.

I just know (from experience) that a regularly used synthetic bag, after 15-20 years, is usually better used as a glorified blanket by that point, and I would no longer depend on the temp rating any more. Just ain't worth the risk.

But again, this is purely my personal speculation, and could be way off on this. But I'd need to see some data to convince me otherwise.

Matt