Good luck! You're doing the right thing. Do it right and do it once and you'll have piece of mind. They will undoubtedly use an all-copper evaporator so it should last for the life of the car.
I like the idea of replacing the vacuum elements while the dash is apart. The tech that replaced my evaporator didn't do this and I have a vacuum actuator which intermittanly makes a "moaning" sound while idling. System works fine but it IS irritating!