I long arm quilt and double bat when I want some real quilt definition. I use an 80/20 on the bottom (Hobbs usually) and then layer it with a washable wool. Using a washable wood instead of 2 layers of 80/20 keeps it from being super heavy and also the wool is loftier than 80/20.
Poly does not "breath", so while it's light weight and warm, it does not allow for presiperation to dissapate--wool does, which is why it's both warm and in hot months does not heat up as much. About the only time I use poly is on quilts that I plan to enter into a show and don't want creases as it resists that more. I especially avoid high loft poly as it tends to lend itself more to puckers when quilting.
For warmth, you might want to make a flannel quilt top and then use either a double bat or wool, and a flannel backing.