Here, for the curious, is the interview with Martin's editor, Anne Groell, in which she discusses cutting off the endings:
SS: One last question. I understand that George wrote more material than could physically fit in A DANCE WITH DRAGONS. Some of it will likely make its way to the next novel, THE WINDS OF WINTER. As his editor, how much say did you have in what stayed and what had to be pushed into the next book?
AG: Well… Probably more say that he would have liked…though many of the choices were his as well. Finishing this book where he absolutely wanted to end it would have taken probably another year and more pages than could be realistically bound between two covers. And so much great stuff had happened already that no one, I felt, could be unsatisfied by the developments. So he voluntarily pulled one big sequence out of the book. I lobbied for another…and it came out, too. People may hold me to blame for this, but I still think it was the right choice. The book is so big and complex and rich and wonderful that adding these two sequences would not have made it any better than it already its.
Based on what he had already written, the two big sequences are almost certainly the battles at Meereen and Winterfell. No book is so "big and complex and rich and wonderful" that you can lop off the ending and expect it to work. And, even without some (justified) cutting, there are ways around page count limits, if you value quality above maximum profit.
Actually, there's only one book with two audio versions, A Feast for Crows
, and both readers are British: John Lee and Roy Dotrice. Dotrice did books 1-3 and 5, but was unavailable when Feast
was recorded, so Lee was brought in. Fans generally seem to have preferred Dotrice (who was also on Martin's TV series Beauty and the Beast
, and played Hallyne in season two of Game of Thrones
after illness prevented him from playing Pycelle), and eventually Feast
was rerecorded with him. Personally, I wasn't wild about either of them, but preferred Lee. Dotrice is more of a performer, doing voices and animated line readings, but he's not always a clear and polished reader, which Lee definitely was.