Doesnt mean anything unless your the orignal owner, not many people buy cars and run them until they blow up.
Although this may be benificial to business's which use them till they fall apart.
Although technicaly the engine / gearbox shouldnt really need replacing if it's had the oil changes and those important weekly oil level checks.
Another thing is porsches get driven very hard, and even though engines and gearboxes shouldnt really wear obviously they wear more if it's been driven hard.