I've wondered myself if we would have joined
DVC if we had access to the Shades of Green resort. I guess the questions you have to ask yourself are:
1. Will you be going to WDW at least every other year for the next few decades?
2. How long are your trips? For shorter trips, the nicer accommodations might not be a big enough plus for you.
3. How many in your family? If more than 4 (now or in future), you have to plan on renting 2BR units. So you'd have to do your cost analysis on that.
4. Are you the types that are in the parks all day and just go to the room to sleep? If so, do you see that changing?
5. Do you think Shades of Green and the military low prices are a "forever" thing, or might Disney discontinue this down the road if times are booming and they know they could charge more?
I'm sure there are more questions, but I think you can see where the general decision points will be coming from.
For us, it was not about saving money. It was about enhancing our vacations.
If you feel the same way, then DVC could be good for you.