My PM is almost 5 years old now. Most of the vehicles weight is up front. I find the stock dampers to be just right. Firm, but well controlled and still comfortable. The rear rides like a buckboard wagon when not loaded. If I pull my 6x10 cargo trailer, it rides much better back there. To be fair, its a work vehicle and meant to carry some load. I am happy enough with the stock dampers, that when it does come time to replace them, I would go with factory components.
My new van is at 163K and I don't know the past history of the shocks (they appear to be the stock ones?), so I am currently replacing all 4 with the Bilstein B6 struts up front and shocks on the rear. I will report back with a review after I get some miles under her.