I once pieced a jacket with rayon batiks. It was very hard. If you are going to use rayons, you just have to realize that they will probably not be very accurate and may not wear well. If you are okay with that, you can use them. Since I was making a jacket that wouldn't have any heavy wear and was a simple design that was okay with much less than perfect accuracy, it worked. I don't think I'd ever try to use it in a quilt.
Polyester double knit frightens me so I don't think I'd ever use that either lol