I've yet to run across the McTrooper, although it looks great online. While I'd rather see NEW figures from the movies, Concept figures and even EU are great opportunities for Hasbro to show us what great figures they can produce. Sometimes they succeed, sometimes they fail.
As a cross between Concept and EU, I think it would be neat if they made figs of all the random character designs that were produced (not only by McQuarrie, but the whole art department) For example, the proto-Bib Fortuna that looked kinda human with a big tall hat-thing. Or some of the pilots and aliens. They would be great on their own or to flesh out dioramas and cantinas.
Speaking of cantina, that would be a cool figure. You know the red-orange Plant/Jelly-fish alien? The one they decided there was no way they could create for the movie back in the day. It would be a challenge for Hasbro, but it'd be a cool fig.