The SCSI card that I will eventually use is the ATTO SE IVD, but it si currently not installed.
IIRC, neither the Sonnet, nor the NewerTech upgrades were compatible with the ATTO SCSI card. I may be misremembering though. The forums where I discussed this back when are either gone or hard to get to. I think we talked about this on the XLR8yourmac.com forums and also at PowerWatch.com (power computing user community).
I might try wiping the hard drive and doing a re-install of OS 9
Is OS 9 supported? I honestly don't know. I ran 7.6.1 with my G3 upgraded 8100-equivalent (PCC Power 120).