So I took a stab at this using some mirror tiles I had sitting around and 48 hours and two treatments of paint remover hasn't made a dent in whatever is on the back of the tiles. Yesterday I went hunting for other mirrors to try and ended up yanking out the full length mirror from the wife's closet while she was away. (We will have to see how long it takes before she notices.). :0
The paint came off the back easily enough and I completed most of the cleanup, although I have yet to cut or measure the reflectivity. I will get to this tomorrow and report back.
David
"Help, help, I'm being repressed!"