UniChris, you gave me a double-take with "recumbent unicycle"--I had to look that up. I wouldn't say they were recumbent, really, just crank-forward ... still. Thanks for sending me on a little exploration journey; I found John Foss's page and some youtube vids. Fun stuff, and things I don't believe I'd ever have thought of. The only pondering I'd ever done about unis was why no one had ever put handlebars on them--yep, they have. That always seemed like an intuitive improvement, but then, you can't juggle.
I tried a uni once, a long time ago; my former brother-in-law had one and I tried it. I think I managed to stay on it for a few seconds and then I quit.
Yeah, that second drive arrangement is pretty problematic and I suspect a working solution might be really energy-inefficient, like for instance, cable drive.