Don't let the super satisfied Casio full meal deal people fool you. Get the Yamaha.
This is the same troll who stated he purchased a PX-850 in a previous thread, and was very happy with it...compared to (cough, cough) a $6000 Roland V-Piano.
DDWalker...I would recommend you consider anyone else's advice, here, on the DP forum, except for Starving Lion. You should read some of his post history. He has stated he is a beginner, yet makes ludicrous claims with regards to Digital Pianos, which only experienced pianists would be able to discriminate.
I don't know why he continues to troll the DP forum, as he has expressed an avowed hatred for any and all digital pianos.
I can tell you, as a person who has years of classical, acoustic piano training and background, that you should be very happy with the new Casio PX-850. I myself selected this model, after careful consideration and weighing the pros and cons (and costs) of various digital pianos in this category.
While the Yamaha CLP-330 is an excellent DP, I believe you will find that the Casio PX-850 has the superior and more current technology both in the sound engine and speaker design. Furthermore, Casio is offering a 3-year extended warranty on the new PX models. I am not sure what type of warranty (if any) you would get with the used (obsolete) Yamaha.