I seriously doubt that a blindfolded driver (certainly any of us in on this thread for sure) will be able to feel the difference between CF roof (obviously with no sunroof) and metal roof with sunroof. I'd place a bet on that as well. Anyone e36jakeo, fueledbymetal, imolazhp_ci ready to put their money where their mouth is???
The CF roof is simply one small piece of the weight/CG engineering effort very effectively implemented by BMW. Not to mention a huge marketing/wow factor. A huge reason they did this was to address the concerns of typical M drivers about weight bloating and to claim M3 weight < 335i weight.
Honestly as much of a contradiction as it is I would choose CF roof + sunroof if offered. The M3 is all about compromise, not a sports car, not a luxury car, not a GT, a bit of each. CF roof + sunroof would be right in line with a weight savings (compared to steel roof with sunroof) and also offer the aural and wind and sun in your face experience of a sunroof. Many generations of M3 have been great track tools with their sunroofs in place so I'll pass on the flames about a sunroof for a track/race car. This ain't no stinking "race car".
Also imolazhp_ci (and others in other threads): I have no idea where you are getting your terminology about "wet CF" and "dry CF"; it is totally wrong. CFRP stands for Carbon Fiber Reinforced Plastic. This is one category of a composite (glue+fibers) just like regular old fiberglass, it is just that these fibers have an incredible strength to weight ratio, better than steel in tension. Once resin (glue) is added to dry CF sheets they are formed and cured through various processes such as RTM or autoclave, etc. With RTM the part may finish with a very smooth glossy finish, other processes may require surfacing and clear coating to achieve a smooth and shiny appearance. For an application like an automotive roof one must carefully choose the resin and clear coat to be UV (sun) resistant and resistant to other common substances that will come into contact with the part (bird droppings are acidic, Hans!). Carbon-carbon is an entirely different beast, used in some very high end brake rotors and very high temperature applications (aero*******. Maybe this is what you meant by "dry", it looks totally dry? Carbon-carbon is manufactured a bit like CFRP but all resin and other additives are literally burnt out of the wet mixture to form carbon-carbon.
Sorry in advance for the CF "rant" but technically incorrect or incorrect jargon in science, engineering or manufacturing get me going (obviously...).
