Please don't talk nonsense. PFS3 does not bypass scsi.device.
PFS3 uses either TD64 or HD_SCSICMD. The former does not work on the standard IDE driver and the latter has a 8GB limit bug on the A1200.
So you *need* either OS3.5/3.9 or IDEfix to overcome the 4GB/8GB limit.
IDEfix supports everything, TD64, NSD64 and SCSI-Direct (HD_SCSICMD). OS3.9 only supports NSD64 and SCSI-Direct, so you have to use PFS3ds on OS3.9.
So IDEfix is always a good choice, even with OS3.9 and PFS3.
Bye,
Thomas