The general rule for me is to use the same fabric in my quilt top. If it is poly/cotton, than use other poly/cotton with it so it all wears and washes the same. I used it to do children's drag along quilts as it washes up well, doesn't wrinkle and keeps it colour well. I have used it for a quilt back on a cotton fabric top with no problems also.
There are a couple of things to remember when using poly/cotton...be careful with the iron (melt or shrinks) don't use it for needle turn appliqué as the edges resist folding under.