Well from my limited experience and what I've heard, one reason UND didnt go with Diamond aircraft was the fact that they are made of fiberglass. Due to extreme hard landing or repeated hard landings, it makes it very expensive/difficult to repair a cracked wing or body, some times even totaling an aircraft. Where as with metal GA aircraft, you can usually pull off a wing, or tail or whatever is damaged and just replace it.
You cant really use that as a source, but it might give you an idea of where to start. Look around, do some searches for aluminum vs. fiberglass aircraft or something similar. GL.