If you get a Raptor 660, get a 2003 or newer model. The '01-'02's were known for having weak transmissions. Just FYI.
Be aware that if you get a Rappy 660, it will require a little more preventative maintenance than a Blaster. Regular oil changes and valve lash checks/adjustments are a MUST if you want the engine to last. Also just know that many 660 Raptors have (like many used quads out there) been ridden hard and neglected. Buy carefully.