I've owned several CCD and CMOS cameras (I'm currently shooting the M9,) but I think that the "look" difference comes down to more than just the type of sensor. Color filters, AA filters (or lack of,) internal processing, raw converter, etc., all play a role in the differences. For example, both Nikon and Canon have been reducing their color filter quality for a while, in order to improve lowlight performance, so simply changing the CFA should make quite a difference.
I'm just not sure that we can isolate differences to simply CCD vs. CMOS, because there are so many elements involved, and Leica may be able to tune the M 240 to look similar to the M9. Granted, I hope that the M9's CCD does prove superior over the M 240 in some ways, so that my M9's value holds, and I'm not tempted to buy the M 240. :ROTFL:
Another thing to consider is that Leica allegedly tuned the M9 sensor to look vaguely like Kodachrome, so, maybe with the M 240, they'll go for some kind of negative film look, like Portra, since the sensor has more DR.