It's clearly a matter of opinion.
The CF thing is mostly about appearance since virtually no one will notice the weight or COG (even if you drove with and without back-to-back).
Once everyone has CF it will be cool to have painted steel. Other car owners are painting their roofs black to give it the look.
Personally, I'd much rather have the moonroof to enjoy the sun and air but I'm in SoCal where that's possible most of the year.
2008 E92 M3 Silverstone II
2006 MB G500 Gelandewagen Irridium Silver
2006 MB SL500 Irridium Silver (wife's)