If you ride all mountain mainly then you better buy that board before somebody else does! I bought mine for $540 so $300 is a steal. It's definitely one of the best boards for riding absolutely EVERYTHING. Back country, groomers, park, etc...
Trust me you won't be disappointed if you buy it. And 151.5 is definitely the size for you, these boards are meant to ride shorter because of the magne-traction.