[Perfectlap]

Seems to me that a car without a service record is often a car without a consistent history of oil changes.

there are a couple of things to wonder about with a no-records car.
1- did the previous owner make a habit of driving the car above 3000 RPM (a good thing), and did the previous owner make a point to drive it at least once for a long distance, I'll say about an hour of driving to and from?
2-did he/she use a quality oil? did they do the sensible thing and change it more frequently than the factory recommended?
3-did they allow the engine enough time once in drive to warm up before they started stomping on the gas? I think most would say about twice the amount of time it takes the coolant to point 12 o'clock north. No high RPM's before that warm up period.

These are all good practices that may not have been followed. For that reason, as there is doubt, you should replace or upgrade (either is fine) the IMSB when you replace the clutch.
Some decide not to wait until the clutch is starting to fail and just do it preemptively once in the high mileage territory. I think this is wise with a car whose history is unknown.

But on the encouraging side, 2000 (early) are most likely dual row bearing cars and S model engines have more robust cylinders which even the Carrera 3.4's did not get. So this at least lowers the likelyhood of at least two common m96 engine failures.