Roadster is significantly worse handling than the coupe. My fully braced ragtop still felt wobbly compared with a stock coupe back to back at Bedford, and the extra 100kg does make a difference too. If you're after a pure drive, then you need the coupe as a base. That said, the roadster is still a great car to drive, I'm purely talking comparatively here.
If you want to put the roof down, then you need the roadster. Obvious yes, but that's really what it boils down to, whether going topless is more important than outright purity of drive.