How long do the OEM Bilsteins usually last? They don't have a great reputation over in E36M3 land, but this car is so much lighter they might last a lot longer. I am just past 30,000 and trying to map out major maintenance the next few years.
It really doesn't have to do much with the weight of the car. The damper failure rate will be related to cycles of suspension motion. The Elise uses shocks, which will be structurally under different stresses than a strut.