Some were told it was 2 years which is below the industry standards as I understand it and less time than it would take to truly evaluate, I'd be surprised if it were under 3 years and suspect it is 3 years. Still, hard to imagine they'd change back to II at this time and with the corporate membership and concessions they demand from the one they're working with, hard to imagine they do both. They considered dual membership around the last renewal with II and decide against it. While I think II is better overall than RCI and much of the benefits of RCI are wasted on DVC (ability to trade up in unit size esp), the truth is that RCI is a better fit due to their points system than is II.
Well, I wouldn't put *too* much stock in that, because Disney is sort of like George Orwell's Oceania: "We've always been at war with Eastasia."
That said, the question regarding affiliation is best answered by asking a different question: which one provides more to Disney's bottom line? RCI has been much more aggressive over the past several years in creating a rental channel for its inventory---and Disney can benefit from that channel to help move developer, breakage, and internal-exchange inventory. Unless and until II is as serious about the rental side of its business, it offers less than RCI can.