gnp61,
When we were looking into buying in at DVC, we were also "leary" of timeshares. My parents own one in Mexico and while they use it to exchange to other locations, the exchange fee (membership fee too) on top of the maintenance seemed to make the costs just as expensive (if not more) as renting on your own with added limitaions of exchange availablity, etc. Also, their timeshare is not worth much if they sell it, if they can even find someone interested in buying it. They still use it but I don't think the $$ was worth it.
Now this is what convinced us about DVC (aside from the fact it is on-site): The resale value has held very, very well - while I don't expect it to keep going up as it has, I don't expect it to drop drastically either (esp. in the next 10 yrs) - there seems to be a good resale market available if we ever had to sell. Another concern is if we can't use the points, we can always rent them (there's a very good market for them), gift them (everyone knows people going to WDW - not necessarily Mexico), or stay at the Plaza in NYC (near home).
The final seller is the flexibilty of the points system - each vacation is different in terms of length and who comes with us. We are no longer regulated to 1 week in a 2-bedroom every year. Not only is this easier for our vacation usage but also if we ever needed to rent our "week" out (NEVER!!). It's hard to find someone who wants to go to XXX for a specific week - easier to find someone already going to Disney and see if their dates are available at DVC. Also, exchanges to Concierge Collection are also on daily points usage so we don't have to give up a whole timeshare week to stay in NYC or D.C. for a few nights.
While we don't anticipate having to give up our points to rent them out, it's nice knowing that the option is available to cover our maintenance fees if our finances take a sudden down turn in the future. Also, there seems to be less risk in our intial investment unlike other timeshares - some of which become worthless.
Hope this helps! Good luck.