I think it depends when and where you go. If you own, you are required to pay maintenance fees, which can (and sometimes do) go up a lot in a given year. Also, unlike buying a deeded week, if you buy MVC points that $3/point junk fee, which is most of the upfront cost, is something you never recover. If you rent from an owner, you just pay a rental fee with no further obligation.
Maintenance fees may or may not be cheaper than rentals. And the question is which maintenance fees (week or points). For example, booking a summer week at Newport Coast Villas (2BR) will cost you 4725 points - you can probably rent that week from an owner for $3600-$4000, which is cheaper than the MFs on the 4725 points. An weeks owner would rent at that price because weeks owners pay MFs or about $1900 (although, getting to the point of MF increases, it was $1430 as recently as 2 years ago). So if you wanted NCV in the summer, there wouldn't be much advantage to owning points. Maybe there was a few years ago when point MFs was in the $0.50s but the advantage has eroded. And if you find other places where owning points is advantageous, it may not stay that way for long.
You may be better off buying a few Marriott deeded weeks and just use them at the locations you are interested in. You may also find more value in looking at the Vistana system (also part of Marriott Vacation Club but has its own internal points exchange system) and buy a resale week at a place like Westin Kierland, which is one of a handful of resorts where resale weeks can also trade internally with points within Westin/Sheraton and Harborside (Atlantis) timeshares. Buying resale at Kierland, or one of the other "mandatory" Vistana resorts will give you access to Westin and Sheratons in Maui, Kauai, Cancun, Myrtle Beach, and Caribbean and a couple of other places.
