well, E9s are pretty 'flexy' cars. the bodies flex and bend when cornering (compared to, say an E3) and, one would imagine, there's only so much power you'd want to have before things need reinforcing, etc. even the windshield is an important part of the body structure, which you realize as soon as you remove one and then watch the body 'sag'. yikes.
cutting the roof off an already flex-prone body is just asking for trouble. also these cars just look plain stupid without the roof.
But to me there is something about a "Coupe"!... When you look at the car, it "DOESN'T" look good with the top down.... of course, I too would question the structural integrity of the covertible in the pictures. Notice he hasn't shown a picture of the "ENTIRE" car with the top down. "SOME" converitbles are nice, but, the 3.0cs as a convertible is NOT! Just like the 635csi convertible, ... It doesn't look good! (Only my personal opinion). Some people think it looks good! But I do know if BMW made this car, structural integrity would not be questionable. Of course this would probably make the car a whole lot heavier. But I must admit, I do like the engine configuration.... (sigh...) But in closing... the 3.0 cs is a gorgeous coupe as the 635. Their lines connect to the overall beauty of the cars. The coupes are solid and light. I love my coupes!... Take care fellas!