I am leery of wool batting now because it bearded through the fabric of the quilt top, and that quilt will now have an itchy feel. I will put a hanging sleeve on it and suggest it be hung. This happened only with the darker fabrics; it was Quilter's Dream wool. I plan to try Hobb's wool batting, but not with dark colors.
The only silk batting I know of is Hobb's Tuscany silk, which does have a small amount of poly. This batting does drape beautifully, but as mentioned above, there isn't much definition with the quilting.
I'm a big fan of the Hobb's wool/cotton batting (I believe it is 20% wool, 80% cotton). It is wonderfully cushy and soft.