Environmental conservation vs. economic development? If you take a long term view, it's a no brainer.
Consider the following: in 1975 Vermont had x number of square miles (I don't know the exact figure). Now in 2004, how many square miles does Vermont have? x, the same number it had in 1975. Now, how much of that fixed amount of land was "developed" (parking lots, ect.) in 1975? The answer is a lot less than it is now. Yet, the development in Vermont has been much, MUCH less than what has happened in New Hampshire, which has become another Massachusetts. Vermont hasn't become that because of ACT 250.
Consider this: development is forever. Once a piece of land goes from being "undeveloped" to being "developed", it never goes back. Fields become parking lots, but parking lots very, VERY rarely become fields. Development is a one way street. With a fixed amount of land and development being a one way street, with more and more land being developed, without any movement in the other direction, it is only a matter of time before Massachusetts and New Hampshire become one big parking lot.
Vermont can go that route or it can stay Vermont. This is a continuous and never ending fight, we must continue to support strong environmental protection and permit laws. We never completely, "win" the battle, we always have to keep fighting to prevent overdevelopment. And if we don't continue fighting, the developers CAN completely win. They could cover the state with pavement. Once it's done, it's done. We can't let that happen.
Let me point out one other thing from an economic standpoint. In the long run, Vermont will be better off economically by staying Vermont and not allowing itself to become another NH or Mass. Why? Because there are TENS OF MILLIONS of tourists in the Northeast, from Philly to Jersey to NYC to Connecticut to the Boston area who want to "get away from it all". Many don't like to fly anymore and would rather drive. They want to go to a place within driving distance which is truly "away from it all". (when you think about it, who could blame them?)
I have friends and relatives in the Boston and New York areas. Years ago, when I would ask them where they were going on vacation this year, they would say, "Vermont, New Hampshire or Maine, I haven't decided yet." Now they don't say that anymore. They say, "Vermont or Maine, I haven't decided yet."