I really prefer the rear projection boards to the front projection Smart boards. In a classroom with special education students there might be a danger of students, or teachers, tripping over cords or knocking the board and then having to reorient the board. A rear projection board might be worth the investment. Another solution would be mounting the projector on the ceiling.
I was also interested in the technology that Anne mentioned in class where the students have a wireless device to answer projected questions. I like that the data can be saved, analyzed and used for reteaching.