I had one of these and as much as I loved it, they just leak and fall apart every other month. You can rectify most of the leaks but it's a constant battle and if your ECU gets damp it is a big expense. Turbo, gearbox actuator and aircon pipes are all common problems. Checkout Smile! it's a smart Roadster. : TheRoadster.net for loads of useful guides and tales of horror. If Daihatsu had made it, I would have bought it in a heartbeat.
I think you’ll find that @Salieri speaks for most of us in that we are all Copen enthusiasts, although I’ve recently jumped ship to a Mazda MX5. Best bet is flog the Smart and then ask nicely if there’s a Copen on here for sale.