I have used Nature's Touch by Pellon. This is very similar in weight to Warm and Natural. Both are needlepunched through scrim. Personally, I would never double this batting because the quilt will become more stiff and more heavy.
Again, personally, I prefer thin and supple quilts (like the vintage/antique quilts). These were/are made with thin cotton batting. The "comforter" look is much newer and came in with polyester batts.