I can recommend the A4091. I have the Commodore version, although the DKB is just as good. Works with everything I've thrown at it so far (CD-RW, Zip, a bunch of HDs ranging from ancient to modern, etc.). You do need a rev.11 Super Buster to use it though, and it doesn't have RAM slots.
Best solution as said is the accellerator with onboard SCSI. I'm swapping the A4091 + CSMk2-060/66MHz for a CSMk3-060/50MHz just for the SCSI. I figure whatever speed I lose on the processor I'll make up for on the file I/O.
