I had a White's Quantum and thought it was a good machine. The only problem I had is that I mainly hunt the beach in the wet sand, and this machine wasn't to good for that, which is why I bought the Minelab Quattro. As far as the dry sand I found it simple, and light to use. Found a lot of clad with it!
I don't know anything about the Prizms though.
Sounds like you're getting a good deal as I sold mine on Ebay for $380.00 in excellent condition!
Good luck with your decision!
HH 8) surfrat96