I can tell you what they will say over on the DVC board.
If you are happy at the All Stars, DVC is unlikely to save you money (although, who knows what will happen over 40 years to hotel rates - dues have typically gone up less than the hotel rack rate). If you stay at moderates (and can limit yourself to studios at DVC), DVC MAY save you money depending on your travel patterns. The kitchen - or even the kitchenette in studios - MAY help as well.
If you stay at Deluxes, and in particular if you require or desire multiple rooms at Deluxes for your family, DVC will likely save you money on your hotel room per trip (of course, many DVC members use this as an excuse to spend more money - more trips, more park passes, more souvieniers, more dinners out). There are other factors - you go at least every three years. You aren't going to go primilarly for long weekends (points are twice as much on Friday and Saturday).
We were getting to the "two connecting rooms at Deluxes" stage. Not because our family is large (two children), but because we prefer to have our children in a different room - or we were traveling with Grandma and Grandpa or someone else. And because we enjoy the deluxe resorts enough to justify staying there over the moderates. So DVC is great for us. But it isn't going to be great for someone who thinks that All Star Movies is fine.
There are some other benefits to DVC - one and two bedroom units have washers and dryers and kitchens. Studios have kitchenettes (small fridges and microwaves), and access to free washers and dryers. But they probably don't add up to enough to be cost effective over the All-Stars.
