I think it has been done, downgrading that is, but I would tell you no that it would not be an option just to play it safe. Don't worry, PPC2k2 is better in many many ways.
If your computer crashes while flashing, well then forgive me but you're screwed. I highly doubt that you'll be able to reflash because your computer won't recognize the device anymore... of course once I misflashed my computer's BIOS and I managed to reflash it somehow

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