I purchased a high mileage TD5 Dual Cab with fsh, but I got it approx $7k cheaper than the going rate. My thoughts being that if anything major went wrong then monies saved on purchase would pay any repair bills.
In my care I spent approx $3k on the engine / maintenance, and I sold it for a $1k more than I paid for it. Mileage was 275,000 when I sold it.

My present County has covered 430,000 kilometres, but again has full history back to 1997. Most of the drivetrain has been replaced, gearbox rebuilt etc. etc. and it drives just as good as the TD5 did.

So I'd think service history is more important than kilometres.