I have used fleece on 3 smaller quilts. I didn't wash it before hand and had no problems with shrinking. My stitches were kind of hidden in the fleece, which was great for any mistakes. (And I make alot!! LOL!!) My little granddaughter loves the fleece backed quilts. She loves to cuddle under them on cold days.
I have never tried the sweatshirt fleece. Doesn't it stretch more than traditional fleece?