I'd thought this was lost, too, so will have to hunt it down at some time when I'm feeling less susceptible to depression (I own the 1984 John Hurt version and think it's superb; I've also seen the 1956 CIA-sponsored version with Edmond O'Brien, though with the more downbeat ending rather than the openly defiant one).

And yes, I'd buy the Criterion boxed set.

Now, if someone would just find the rest of 'The Caves of Steel'..