The short version of Macbeth, with the opening narration, is the Welles-approved studio-compromise release version and is quite hard to find (though every now and then I see it available on DVD in France for a day or two.)
The long version is either the Welles-approved rough cut or preview cut, or a reconstruction of same done by the Folger Shakespeare Library (when they weren't drinking coffee.)
Both are good versions of the film, and I found I enjoyed the shorter one more, for whatever reason (though my print of it is quite poor, and thanks again to the long-lost Mteal for sharing that.)
But I'm the guy who thinks Falstaff would be better less twenty minutes (goodbye Shallow and Silence recruiting scene from the first half and I haven't decided what from the second.) Why? Pacing, primarily. Chimes gallops along until it bogs down in quicksand, and that's no place for a film to be. And no screeching cockatiel with a transparent eye to "wake 'em up" either.
If TOSOTW is released, of course there will be mixed feelings about it. I'll be hesitant about the new PB footage for the opening or frame, fascinated by the Welles footage, and focused like "Bill Clinton on the economy" on the editing to see if I can discern the new splices from the 1970s ones done by Welles.
Its brothers, sisters, or transgenders will be the other reconstructed unreleased films, the likes of Don Quijote (ouch,) It's All True (gawd, but "Four Men on a Raft" is gorgeous,) and the many projects headed by Stefan (all of which I've enjoyed, or the generous portion I've seen at least.)
That's not bad company.
Others will say "crap reconstruction of crap original film," after which with freshly vented spleen they may go have a nice nap.
A Callow error? There were a lot of them in his second book Hello Americans, which is why I didn't finish reading it. It should have a place on my Welles shelf though, seeing as two Higgam books lurk there already (no David Thomson however; there I draw the line.)
Sto Pro Veritate