[Perfectlap]

I think how that engine was looked after has more to do with it. In other words I think you might be missing a big part of the issue if you don't consider the owner and look at it just based tip vs. manual. The IMS has inherit issues that are made worse by insufficient oil changes, inadequate oils, insufficient driving (I would not buy an annualy winter stored Boxster/996), and as landrovered points out, insufficient revving.

I'd be really curious to see a profile of what sorts of avearge weekly miles, (year round driver vs. summer only), if Mobil 1 (now questioned as inadquate) was used, if the oil was not changed at least twice a year, for those cars that experienced IMS failure.