I have the Earl Klugh Alvarez....very nice nylon. Mine was before on board pre-amps, so you have to use a separate unit...a little inconvenient, but works fine.
300 students is a load. I had a studio in the 70's with around 200 students (in the winter-they all disappeared in the summer).
I'll look at the Alvarez line to see if there is something I like and let you guys know...
Russ