When looking at benchmarks between the two, make sure the clock rates are the same. rolli59 link shows several percent different in benchmarks, but the graphics is clocked higher and the ram is clocked higher.
Personally my 1gig version will clock to 1.2GHz, but the ram hates being overclocked. I doubt the price will make it a pick over the 1gig model or a 7850, but hard to argue with options!