I'd suggest that latencies are not an issue. Considering that the slowest of the Acard adapters can do ultra speeds (20 MB/sec) and I've seen 7726Q devices do in excess of 100 MB/sec, the total latency is probably unmeasurable on m68k hardware. Any measurable latency would make it very difficult to attain those speeds.
Seeing how two CF cards can be completely different speeds via five different environments bears out that much of it may be down to what modes the cards and devices connecting the cards can attain. I've tested SSD-SCSI, CF-SATA-SCSI, CF-SCSI direct (in a nice SCSI card reader: http://a4000t.com/store/index.php?main_page=product_info&cPath=65_79&products_id=195), CF-Addonics-IDE-SCSI, and CF-Addonics-IDE. A fast card goes as fast as the computer's SCSI bus, and a slower card is noticeably slower even on a modest machine.
Seeing how two CF cards can be completely different speeds via five different environments bears out that much of it may be down to what modes the cards and devices connecting the cards can attain. I've tested SSD-SCSI, CF-SATA-SCSI, CF-SCSI direct (in a nice SCSI card reader: http://a4000t.com/store/index.php?main_page=product_info&cPath=65_79&products_id=195), CF-Addonics-IDE-SCSI, and CF-Addonics-IDE. A fast card goes as fast as the computer's SCSI bus, and a slower card is noticeably slower even on a modest machine.