What are the "real" reasons why we don't want to keep machinery as long as we once did?  It wasn't too long ago kept tractors and combines up to 15 years before ever considering a new replacement (still do on some items).  We always budgeted to make sure everything was paid for long before trade in, we weren't affraid to buy parts and work on it ourselves, etc.  One of the most common things I hear are "we don't want anything out of warranty."  Three likely reasons why: 1) can't afford it, 2) not smart enough to work on it 3) aging farmers not in shape to work on things like they use to. 

I just think in this day and age of our economy, trading/rolling so frequently doesn't make nearly as much sense as building your equity position by paying off machinery, etc.  I'd be interested in hearing your opinoins.