Threw a $60 offer at this thing and was accepted.
This thing seems to be INSANE going by the datasheet. It's a two-drive SCSI to PC card device that supports two PC card drives, each on a separate LUN under one ID. It can support them as fixed disks, removable disks or a DAT drive. It just takes PC cards, so supports CF cards in a PC card adapter. For systems that don't support multiple LUNs, it can apparently combine the drives into one, but I'm not sure how this is done.
In theory I should be able to use this device identically to a SCSI2SD, except this device does more and acts like two separate drives in one, so on some systems I could have one drive act as OS and another act like a zip drive containing other software. Then I could just move it between vintage platforms, swapping the CF cards for ones with different filesystems.