I am at Mountain Vista now (nicer place than I thought it would be).
Last Sunday, my wife and I purchased 2 2-br Platinum lockoffs at Lagunamar for $21,450 each (one even; one odd) and used them to retro our 2 non-developer purchases at Kierland (148,100 options) and Harborside (196,900 options) - and to achieve 5* status at the old, 559,000 level.
Since the announcement came out yesterday, I immediately ran upstairs to the sales office today and asked about being grandfathered. I was directed to a document entitled: Starwood Vacation Network Elite Level Enrollment Form - which states that as of September 14, 2008 we are Five Star SVN Elite Members. I was told that because of the dates on the agreements and because the document had been issued on that date, we were grandfathered.
If there is any problem at a later time, we intend to use these documents as proof of the date we became 5*. I believe that anyone who earlier achieved 5* was given a similar document in the purchase package. So, I don't expect problems, but we'll just have to see.