I know there is a service guy over by Mount Union that is supposed to be pretty good but we haven't dealt with him yet.  There is another guy, it seems like he might be from the Columbus Junction area who was down and did some engine work on a neighbors tractor a couple years ago and he seemed like a really sharp guy.  The Cat service will cost a little more but when one of their trucks rolls into your driveway it really is a shop on wheels.  From your mapdot it looks like your probably close enough to Cedar Rapids that getting parts wouldn't be a big deal if it's something you can't wait for them to deliver. 

A neighbor traded his two year old 570R for a new one for next year and said he is trading for around $10/acre which isn't bad and I'm guessing the machine he's trading off has around 1.5 million bushels through it with no wear parts replaced.  Last year they replaced a couple of switches and a sensor but this year they never touched it all season.