"Can the Microvision accept the show disk from the Expression?" The show disk: no. The show file: yes, if converted from Expression I format to MicroVision format using ETCedit. You may need a pre-XP machine to do this--I haven't used ETCedit in about fifteen years, and it's a DOS-only program.
Follow this link for the Manual: http://www.etcconnect.com/docs/docs_downloads/manuals/etceditm.pdf
And this for the program: http://www.etcconnect.com/docs/docs_downloads/console/ETC_EDIT.zip
Sidenote, I would ask a different question: "Can an Expression I file be converted to an Expression 2x or 3 or Express?" as I suspect you'll find many more of those consoles available. (And I'm curious myself to know the answer to that one.)