I think a lot of this depends on the crystal ball. With DVC "past experience is no guantee of future performance." Its a long contract, if DVC builds another big resort, that will only increase competition for the smaller resorts. If they build a lot of offsite resorts, that may change things as well. Also, as people become more knowledgeable about their contracts and discover that the smaller resorts book faster, they will call faster, making it more difficult to book. I look at this sort of like ADRs - who'd have guessed Cindy's would now be relatively easy to get and Le Cellier would be the difficult reservation....we used to walk into Le Cellier - but if you have a favorite, wouldn't you take an advantage in getting it?
There is also the matter of how picky you are and how stressed you are willing to be. A guarenteed two beds in the second bedroom at BCV at seven months is unlikely - any room at all if you call promptly - likely most times of the year - especially if you can use the wait list and have some flexibility.
How stressed - we get posts all the time about "I didn't have a problem at all...I got what I wanted...Friday and Saturday were available right way, and Wednesday, I went on the waitlist for Monday, Tuesday and Thursday, but Monday and Tuesday came through in a few days and Thursday came through a few weeks after." I'm really happy these people got what they wanted, but I'm too much of a worrier, I just want to book it.
How timely you are - with a few exceptions, you can pretty much call at 11, 10 or nine months at "home" and get what you want....However, you need to be much prompter when working with a low supply resort at seven months.
Basically, if you are content "just being at Disney" you will be fine with DVC. If you need to stay somewhere specific, you should buy there. If you get your heart set on a different resort for each trip, you might want to rethink DVC...