Replying to AR7 or Mastermind?

Hello, my name is Paul and I ski in southern California. I am new to park and it is the only thing to do at my home mountain. I was wondering whether the AR7 is worth the extra cash since i am new to park. I am looking for something forgiving and durable. I am 17, 5'11, 145 pounds and my budget is a little over $500 without bindings.

What do you guys think? Any other skis i should demo during this Christmas at Mammoth?

Thanks NS.