Any kind of Muslin has always been my go-to for piecing, applique, and backing, I love how it feels when I'm working with it and I love how it looks in a quilt. I'm making a Double Wedding Ring for my younger sister, it'll have Muslin as the background but I'm using either Ivory or Natural, I just can't make up my mind yet, lol.
It is correct that it does shrink, however, so you need to make sure to prewash your Muslin before you start quilting with it. A simple wash in warm water, dry it in the dryer, then press and you're good to go. I usually wash mine twice, that's just me being on the safe side but it is a good practice to start getting into the habit of doing.