Finally, Interval often offers a 2 for 1 exchange for desirable resorts such as Ko Olina.
As a note to the 2 for 1 ACs from Interval, these are offered when you deposit your week with Interval so you can get an additional week for around 199-299 (depending on room size). However, these are getting VERY restrictive, even when your initial deposit is a high value week, so you are limited to where you can use this additional week.
The real advantage, IMO, to owning at KoOlina is if you use it frequently and need to travel there in the high season. If you use FF miles to save $$$, then you can guarantee your dates before the 330 day FF booking period. Also, if you buy an ocean view, then you can also be guaranteed your view category (when trading in, it's a crapshoot). You can still rent OV for not much above MF at times, but you would have to watch to catch those deals.
If you can travel at the last moment (less than 60day notice), or you can travel in slower periods, you can find a lower maintenance fee Marriott TS & get to KoOlina without a lot of difficulty. No one knows how weeks trading will go in the future, but I suspect since the points systems has a TON of KoOlina weeks, Marriott will deposit these to Interval when it needs to snag other high value weeks out of Interval to fulfill points requests.
If you plan to trade out a lot, it's really a bad deal for trading when you consider maintenance fees - unless you also want other higher value weeks (then you are guaranteed good trade value). Some people get around this by renting out their higher value weeks & then pay for their "cheaper" trade with the proceeds.