Jason, my '05 X-star MCX is basically the same boat.
I did run the OJ 14.25 X 14.5 prop.....really good holeshot but lost some top speed and would hit the rev-limiter pretty easy.
I now run the OJ 14.75 X 15.5 and I really like it better. We run about the same ballast as you and 5-6 people in the boat.
Take into account that I'm at sea level, so as stated above talk to Eric @ OJ for some advise. High altitudes will make that MCX work pretty hard I believe, so maybe in your case the 14.25 X 14.5 might be best.
I was njskier on here.