That's awesome guys, thanks for testing it for me..
i'm going to put a link on my page, http://superdrive.cynikal.net/
to this forum as user testimonials..
i'm glad i could be of help to the mac community, thanks for the support (and your braveness) and enjoy!!!
On a more serious note, i think desmond has a very good point about the heat dissipation. I added to my firmware page about the possible reasons for why it was limited to 1x and one of them was heat. If your powerbook has gets hotter than usual, you shouldn't burn at the higher speeds. This is especially true in summer (now in northern hemisphere), as the ambient temperatures (if you aren't in an air conditioned room) are higher, and there is less cold air to cool your powerbook. If you're in a warm environment, i'd strongly recommend not burning at the higher speeds. Otherwise your powerbook may overheat.
This also applies if your system is already hot before you burn anything from high CPU/hard drive usage. I have a CPU meter in my dock to tell me if there's a run-away application that is slowing my computer down (and heating it up). I wouldn't burn at 2X unless i left my powerbook cool down after i kill -9 the rogue process.