It worked for us. In the computer science and management courses we had there was always need for the students to be admins, plus which OS needed to be on the machine changed depending on the class.
Of course it's not a good idea if students needed to keep things on the system, although ours were always told to take everything with them. More than once a student came back saying he left such-and-such file on the system. Too bad.
What size drives did you have? I’m surprised you could reimage between classes.