How much of a difference is there between the two,
really?
The big difference is the addition of bus disconnect/reconnect in SCSI.
SASI devices hogged the bus until a transaction completed, which didn't
work well for high latency operations like tape seeks/rewinds.
An NCR 5380 SCSI controller will work fine with SASI devices. At one
point it was easy to find them on ISA cards, haven't looked lately.
Mixing SASI/SCSI on the same bus is problematic if the SCSI devices try to
disconnect.