This is something I've never really got my head around, I guess because I don't really understand this form of measurement? A vehicle's mileage is quite clear - under 50,000 generally means plenty of life left, 100,000 means small engines are tired but bigger ones are generally ok if maintained well, then 250,000 would be pretty much worth forgetting unless lots of work has been done.
How do operating hours work? What's considered a sensible cut off point for a mog engine where you would view it as risky or tired?