For what is my experience I recommend without reserve the ATTO PSC board, it is really a little wonder, your best friend in SCSI dealing from OS9 to OSX5, it fully support boot (from CD or DVD too) and mixed devices, it is cheap but very well supported from ATTO. I would not recommend the UL2D, it is not so compatible and versatile like the PSC.
Acard board are also very good, I owned a 67162M and performed very well but since I don't need performances but only compatibility I sold it and stick with the PSC :-) Believe me, it is really a swiss knife, absolutely nothing to do with Adaptec, the worse SCSI experience you will ever try on a Mac...