Oh Pat, gonna have to buck ya here. Maybe other quilting ladies will come forward in this as well. For me:
No polyester in quilting. Only 100% cotton in quilting. Quilts lasted ages due to the fact fabric was made very well way back in the day. They had no synthetics..only the good, hearty stuff.
Problem being with synthetics, they lose their shape in time becoming "bunchy". Quilters have a tendency to iron their blocks as they go. Snythetics are not tolerant of hot irons with steam. Polyester will melt all over that iron. Synthetics have sizing; making the fabric stiff. Even after pre-washing, not soft as cotton and not as forgiving when sewing. In time, I believe polyester breaks down and tears very easily and does separate at the seams. I, personally, do not see many 1960s still around.
When Wal-Mart moved in two towns away, I remember the quilting ladies complaining that Wal-Mart only carried polyester/cotton blends. AND then slowly, 100% cotton started showing up on Wal-Mart's shelves.
I won't even sew my quilts with polyester thread. Only 100% cotton in sewing pieces together and in free-motion quilting.