I emailed them and later called them and they sent me three wool samples each about 15 " square. The wool has nice loft but not the heat of polyester. I bet they would send you samples of both.
Via the email from Jane: "The Dream Cotton select is only slightly heavier with 4 ounces of fiber per square yard and is still quite thin, but it is much easier to use on the machine (than Dream Request) because you don't have to be quite as delicate with it. The Dream Wool has 3.5 ounces per square yard, but it is much loftier - it has approximately 1/3 - 1/2" of loft, but because is light weight, it compresses well for hand quilting, and is also great for machine quilting. The Dream Wool is slightly warmer than the Dream Cotton select weight."
i love their products.