When you buy points, you end up paying around 50% more in maintenance fees for the overhead of managing the collection trust. However, points certainly give you more flexibility, and provide partial protection from unusually large special assessments at individual properties. The trust owns the deeded weeks, so it still has to pay the assessments. Since the trusts own many weeks at many resorts, the impact of the assessments is lessened.
If you don't mind booking by the week, Diamond's own exchange program makes it easy to try other properties. If your ownership is one of the lower tier resorts, you can pan extra to book a higher tier resort. However, if you own at a higher tier resort, it seems like a waste of money to exchange it for a lower tier resort.
When we bought from the developer (

) in 2004, they sold us a deeded with that came with Club membership. We get the lower maintenance fees, but the flexibility of booking with points. They didn't do that for very long before they started selling only points. Unfortunately, if we ever sell the deed, the Club membership will not get transferred to the buyer. We like staying at the same place each year, The Point at Poipu, so when we wanted to buy again, we bought deeded weeks on the resale market, at a fraction of the price we paid for the first week.