The roadster roof down looks ace. Roof up it still looks ok but not quite so stunning imho. I,ve owned both and the roadster handles the same but is heavier and it shows under acceleration.
I,ve currently got a 420 turbo diesel m sport convertible as well as my HR coupe. No problems with space for a six footer in either car. However, the drive is completely different between each car . The Zed is less comfortable on a long run but far more responsive. The Beemer is a good comfortable cruiser and will use half as much fuel. It can shift in sport + mode but doesn't,t compare with Zed for thrill factor.
To sum up. Buy the Zed for white knuckle driving and the Beemer for everyday journeys.