I've been tempted to do that for the same reason. However, my personal solution is to put a quilt on top of my duvet-covered comforter. I don't like the look of the comforter being all puffy and not laying flat. The quilt holds it down and looks pretty. We just throw it back when we go to bed.
If you do decide to use a quilt for a duvet cover, I would definitely suggest backing it with something and quilting it before making it into a cover.