I'll be grateful for people's experience with these products, or
knowledge about them. (I've also done some googling, but what I find
seems to be mostly contractors rather than homeowners.)

I have a 50-year-old house, cinder-block basement walls. All
insulation, studs, sill plates had to be removed because of mold. Now
it's time to re-insulate.

My mold guy recommends Reflectix, but http://reflectixinc.com
promises an R of only 6.1, and that's if you also put in an interior
wall. Demilec closed-cell foam promises R=14 with a two-inch layer,
with no interior wall required. Both promise to stop radon and water
vapor.

The basement will be used for storage, laundry, a workshop, and
exercise equipment, so appearance isn't a concern just yet. Maybe in
a few years I'll be able to afford to turn part of it into a guest
room, but I can always frame and drywall that part at that time.

--
Stan Brown, Oak Road Systems, Tompkins County, New York, USA
http://OakRoadSystems.com/
"If there's one thing I know, it's men. I ought to: it's
been my life work." -- Marie Dressler, in /Dinner at Eight/