There are reports (notably on TUG's website) about changes coming in June of 2010 in the Marriott world. From what I read there Marriott will move from a "weeks" program to a "points" approach perhaps similar to the Hilton (HGVC) approach... however, unlike the Hilton program, Marriott will reportedly differentiate between those who bought directly from Marriott and those who bought "resale" from current owners. The rumor is that they will offer current owners an opportunity to "upgrade" their weeks membership for the ability to internally trade without Interval International...the cost of upgrade will be minimal for those who directly purchased from Marriott...and significantly higher for resale owners. This will have the effect of lowering the value of the asset by current members, as buyers will undoubtedly adjust their bids and offers for these properties. I imagine that Interval will continue to provide trades for non-upgrading Marriott owners but it is unclear what will happen to the preferential treatment for Marriott to Marriott exchanges.
We will all have to wait until the actual roll out of this "improvement"... if you bought from Marriott and have a Platinum week you should like what you see...if you are resale or own a lesser desirable season...not so much.
Douglas A.