Long test-drive is the best advise of course
IMO PASM offers both, more comfort and less body roll at the same time. I can recommend it, but it's an individual choice of course. The car with the stock suspension may be more predictable at the limit, but I found that I can go faster through the corners with a PASM car. Regarding track use: on a smooth surface PASM in sports mode is great, on a more rough track (like Nordschleife) I prefer to drive in normal mode + SC on. Never drove a Boxster with stock suspension on a track, so I can't compare. For now and then amateur racing PASM is absolutely fine, if you want to take it seriously IMO you need another suspension anyway (maybe even another car
).