I’ve looked at a copy of Miller’s adaptation now, which I’d never seen or read before, and I’ve added some more thoughts to my post about the play.

Short version: It seems to me that Miller’s adaptation is very different from Ibsen’s original in a crucial way, presenting Stockmann as seriously heroic where Ibsen presents him as comically misguided. So The Great Divide seems to be inspired by Miller’s adaptation, not Ibsen’s play. Whether that’s a good thing probably depends on how you feel about the Miller and Ibsen versions.