Just to respond to myself.....I finally set up this IOGear USB KVM this afternoon (serving 2 Linux machines, a Win2K desktop and a Win2K work laptop connected to a port replicator) and it works quite well.

WRT the original subject, I have *not* tried to connect a shareed USB device yet -- I can not decide what to share! -- but everything else works well. My one criticism: there's a bit of a delay when switching -- it takes a few seconds for the USB mouse/keyuboard to be detected on the new machine.

I got an IBM compact USB keyboard to make this work. It works OK, but I would rather have a full-size 104/105 USB keyboard. OTOH, I am thrilled with my Logitech cordless optical USB mouse.