I have the silk MEC rectangular liner. I wanted to protect my new sleeping bag. Used it once only, or rather tried to, but I didn't like the feel of it and ditched it after 10 minutes. Other people swear by them, though.
(I used a cotton one many years ago backpacking in Europe. Guess I got used to it--silk felt weird.)
Anyway, PM me. I could send it to you to try out, if you want.