And since all my information is based on a few conversations I've had recently, I was a little hesitant about sharing, but I was lucky enough to be at that concert.
I didn't know any of the back story at the time. I just saw Prince and Sondheim hug and figured all was well with them.
Morrison said ( to me and I think it was in her recent show) that "I know now that the big problem was the book."
snap
But as you said, the original ending was powerful.
I wonder what Furth could possibly have disliked about that original production so much that he wouldn't even give it a shot in the reunion concert.