There are a few important updates that need to be done to all the quads. The most important is the stud/stage 8 update. I did the stage 8 since it covers more of the bolts. There is also a motor mounts update, oil line update, yada yada yada. Check this out....
service bulletins stage 8 There are people that have had great luck with their dale and those that have horrible luck with their dale. I have an 02 dale with updates that is running like a charm. From what you said it is a later model engine, chances are it will need crank work at some point. No telling when that will be. You can use that as a buying point with the seller. Bearing issues is what will get ya on the crank, 600 bucks to fix or 750 for a new crank. I would go with the 750 since it is completely rebuildable.
I am just throwing out there the could be's. This dale may run great for years, much of the reliablitly lies on the owners shoulders. Usages, maintainance, etc......