I've been looking for a new digital piano for a while and am most impressed with the Yamaha P-Series. I've been looking at the newest model, the P155, which costs about $1200 new, and is very impressive, modern, top of the line for its price range. I've also seen Yamaha P120s, used, for anywhere from $500-$700. Obviously I would save a lot of money with the P120, but do you think that the P155 would be the better investment?