As anybody who reads my posts knows, I'm no expert. To me, however, 156 hours seems like a lot on a demo tractor. My guess is that a demo tractor is going to get used hard -- kinda like a rental car only more so.
When I go to demo a tractor, I drive it hard. I try to see how much it can do, and how it reacts when I do some of the stupid things that I hope I never do in the field. Like how tight can this thing turn? What happens if I'm moving forwards and I jam on the reverse? What happens if my clumsy foot doesn't make it all the way over to the reverse pedal and I jam on both pedals at once? This is just on the lot. If I got one out to my place to try to work with it, I'd want to know how much this loader can really lift. How fast does it really go up and down? I'd be trying to push it to the limit in everything I tried.
Still, that doesn't mean that you shouldn't buy the demo tractor. I just would consider 156 demo hours as more than 156 "regular" hours.
-- Grant