Which Boxster is best? Three choices for everyone to ponder!

[Perfectlap]

I was owner #3 before the car had reached 9K miles. The car was showroom mint with a BIG discount. SCORE.

Cars that sit a long time with low miles are indeed a concern if the owners have not regularly changed the oil. The IMS bearing being the biggest concern there.
A car like that should have that part upgraded as a first order of business.
If you are buying from a private owner maybe ask for an oil change as part of the test, cut open the oil filter and see if you spot any metal fragments bigger than freshly cracked pepper. A dealer lot would most likely have changed the oil when the car first arrived so this test my lose its value. On the other hand maybe the dealer doesn't bother to put the money into. If you do spot the fragments that's a sign that maybe the IMS bearing is well into its self-implosion and the engine is sitting on a grenade. But you should also understand that this can be the case with a high mileage one owner car where the oil was also not changed regularly.
I guess mileage isn't really the issue so much as how much routine maintenance, six month oil changes, the car has received. My car had only had one or two oil changes in its first four years but once I took ownership I changed that right away.
When the bearing was extracted (dual row) at 69K miles they found it to be in perfect condition.