Whoa! Thanks for the wholehearted response! That confirms my thoughts while looking at then in the store.
I have since seen Terramar brand silks,sold by Sirra Trading Post! at about 1/2 the price of the REI's. I wonder if I'll be glad I saved the money or sorry I made a bad decision?
I definitely want them to be lightweight to protect the sleeping bag in summer, not for insulation