I guess it all depends on what you want to do with it. I have had 3 600 SDI's they are a great motor. About the only 2 smoke I will own. No need for premium fuel, sips oil, and 18 MPG!
I would agree with the post above. Clutch Kit = Best bang for the $. If you are going to do any off-trail stuff get rid of the 5.7's. Great trail ski but not so good for floatation.