Chainsaw Ash,
I would definitely upgrade if you want to do dual layer. It also burns discs faster. I don't know if that is an issue for you or not. I know everyone likes faster burners, but I have been happy enough with 4x since burning a DVD takes so much less time than converting an AVI file to MPEG-2. I'll gladly upgrade and use 8x and 12x discs if they are priced right and reliable though.
Thanks.
Patrick