I'm going to say something controversial now, so be warned!
I have just watched an onboard lap with Schumacher (
http://www.f1zone.net/forum/viewtopic.p ... 94#p279694) and I actually think the front f-duct should be banned from subsequent races.
What is clear from that video is that Schumacher is having to come off the DRS about two seconds before braking for a corner. Clearly it takes time for the device to adjust airflow and for the flow to reattach to the front wing. In my mind that is very dangerous as if something unexpected happens in front of them, such as another car crashing, they may not be able to deactivate the DRS and get the car back under control quickly enough to be able to react. If flow was reattaching instantly then fine but because of that safety margin that they're using in qualifying, when surely they're pushing it as close as they dare, then there is scope for some very dangerous situations. For example if a car gets into problems in front of them and they slam on the brakes whilst DRS is active, then there will be a 1 to 2 second window where the rear wing is at full downforce and the front wing is still stalled. This means that during this period the car is both unstable and lacking front downforce at a time when it is most needed (under heavy braking and probably wanting to change direction).
So whilst it's a great bit of engineering and a very clever interpretation of the rules, I personally believe it is unsafe.