I use an SDHC Card fitted to an IDE Adapter, which in turn is connected to an IDE to SCSI bridge, which in turn is fitted to my CyberSCSI Mk2.
It works nice and fast, silent and stable too.
You might want to use PFS too.
That's the first recommendation I've heard for SDHC. Others have told me its less reliable then Compact Flash.
Thanks Nicholas. I think I might like to try something like that on my Powermac.