I've got a Lite-On IDE CD-RW (48x 32x 16x) drive I wanted to put into my G3 to give it burning capabilities (and something better than the stock 24x drive), but there is something about it that kills MacOS 9 completely.
Drive plugged in, start OS 9 - it says Welcome to MacOS, and before the progress bar appears - it locks up totally. Only 0.01% of the time do I get a successful boot sequence. I've tried various versions and hacks of the CD driver but to no avail. OS X loves it - but then again it's Unix at heart and doesn't really care but CDs fail to burn at anything higher than 12x, but I put that down to the IDE bus.
I had a similar problem with a generic CD-ROM drive (I think it was a 50x drive). Froze on OS9 startup.