I have heard this more than once. I had reservations too. After the front bumper cap was installed, however, the "shelf" does not stand out and actually complements the look IMHO.
Considering the CTR YB was very purposefull in design to reach 200+ mph, there must be a function of the shelf. I doubt ALois just made it a straight plane just because. I am thinking it actually serves to increase downforce on the front end. The front end of hte 911 has a slight nose down attitute. When the shelf is positioned with this nose down attitude it seems that air flowing over the front end would be directed at pushing the nose of the car down. I would think the "shelf" would do this much better than the rounded sillouette of the OEM bumper.
Anyone hear anything on this?