I've been using my C860 this way on occasion. The one problem I've noticed is that the Z can't seem to keep up with a continuous data stream.
For example, I'll drag a CD-full of MP3's to the Z (as USBMSD) in Konquerer: a bunch of data gets sent and then K says that the transfer has stalled. After a delay, it'll resume, send a bunch of data, then stall again. It'll continue like this until the transfer is finished. When it stalls it's usually for 10 seconds or more. All in all, it seems to take significantly longer than other devices.
This is on a USB 2.0 hub, BTW. Does the Z USB interface only support USB 1.1? That might explain this, I suppose.
Otherwise, does anyone know of a way to correct this?
~ray