I can vouch for the 6501 color is very consistent, and we have had few service calls. My only gripe is that they will only let us order one toner of each color at a time. There are jobs that we run that can use a full yellow toner in 4-5 hours run time. We then have to wait for another order. Very frustrating.
I have two KM 6500s we are about ready to replace. They have been nice machines even though we run the hell out of them...from 200,000 - 500,000 impressions a month between them. Our dealer, a Global Imaging company, now a wholly owned subsidiary of Xerox, has always kept us very well stocked on toner. We always have at least 12 bottles of each on hand.
How parts and consumables are distributed will be heavily weighted in our RFP analysis. Rationing out toner parts that are included in our service contract would not be acceptable.