carddisk.device is not able to handle CF cards.
In terms of using them, it seems that way At least Prepcard can read the card vendor and type (if it's on the card).
However, floppy users seem to have a problem with using large PCMCIA cards (over 2GB).
I can't help but thing it is not just compactflash.device involved, setpatch if the only component that is involved with the process for users with old ROMs and new hard drives,
Anyway, I'm just talking to myself here, seems nobody else thinking along these lines of why.
EDIT: My thinking here is that different setpatch versions on 3.1 machines do have an effect on TD64 working, Therefore, on a machine with just a 3.0 or a 2.0 setpatch, TD64 implementation is not fully present and large capacity drives (specifically PCMCIA cards) cannot work properly.
It's obviously down to me to test this hypothesis, it's not established as fact yet.
EDIT. Thank you Olsen, an old workbench,library is a definite contender. Big (>4gb) PCMCIA card seems to be working but craps out when it is filled too much.