I had 4 hard drives in my Gigabit G4. As long as jumper settings are set. It works. Sure I had no optical drive, but it worked.

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I think the point of this thread is that normally Rev 1 B&Ws are known to have drive corruption issues when using a slave drive.(at least on the bus the HDDs were on by default or something, been a while since I looked into it so cannot remember exactly) It was fixed in the Rev 2.
Guys, as I recall there was an app written specifically for testing HDD corruption floating around the internet. You would need O S9 to run it though.