This sexy machine:
http://www.rainnea.com/cnc_5axis.htm
Uses two motors, at least the older version did.
Apparently it is not a good idea as the motors can tend to fight each other however I understand he had no problems although I don't think he was taking heavy cuts.
Balendo who is a bit of an expert on these things suggests belts are better so that is what I intend to do.
Graham