emusonacid!

What if I used Mosrob's idea with an external case&power, but instead of a CF card reader->ide used a standard passive USB card reader. Then I also made an usb connector available on the front of the unit(eg. for a Memory Stick). The internal usb's are then connected toghether with a powered USB-hub (providing the power for all devices). Then I use a USB->SCSI converter (cable) that connects the whole thing to the external SCSI-bus.

Would this combo of memory devices be visible to my E4 and/or my Mac which are both on the external SCSI-bus? (If so it would be dream as this would provide us old users on mac os9 with a hot-swapable usb-bus: by powering on/of this external unit). All memory devices would be formatted as FAT32.

Is this realistic? :)

Hmm, this sounds complicated.
In Germany we would describe this technic as "Von hinten durch die Brust ins Auge" ...
or as people from Texas would say: "He'd go through a horse's ass to get to its mouth"

This cannot work as there is no USB-to-IDE Bridge adapter and the cardreader & everything that is connected to it will not be recognized by EOS.
Also the solution with a USB-to-SCSI adapter will not work as the USB-part of this solution is always a plug (Type A) and not a socket (Type B) and you need a device driver to get this cable working with your PC/Mac. There has to be a driver for EOS to get the USB-adapter, the USB-Hub and the USB-Stick recognized.

See here: Ratoc USB2.0 to Ultra SCSI Converter U2SCX http://www.ratocsystems.com/english/products/U2SCX.html
This will not work with EOS if there is no PC/Mac this cable is connected to.
AND: you can connect just one SCSI-device to this cable, not a SCSI-chain with 1-7 SCSI-devices.

The reason why a Compact Flash card is working with this CF-2-IDE Bridge is because CF Cards have an integrated IDE interface.