The Acard is not a cheap solution but the fact that "it just works", provides a nice speedup and is nearly inaudible are worth the money to me! Also it allows me to use new drives for now and the next X years, instead of relying on older and older SCSI drives.
Of topic, I remember some other Dutch Amiga fans getting ~30MB/s on the CSPPC UW SCSI interface. Definitely out of reach with the (theoretical max) 10MB/s interface on my cards...