In a separate thread, codes65536 says FW for DL is questionable on the 851S. I just purchased a Buslink/Lite-On 851 before I knew about the 821 being able to upgrade to DL (I guess knowledge is power). My question is, how questionable is the DL upgrade for the 851S? Should I return the 851S and spring the extra $15 for the 812? There's nothing wrong with the 851S, I love it. It does 4x on the cheap Shop4Tech Yi Jhan 1x media beautifully!