The F-duct boosts speed, but is surely activated at the start of the straight, once maximum downforce is no longer required, not after the car has reached what would otherwise be its maximum speed. I don’t think drivers waited until the car stopped accelerating to activate the F-duct, so there was no sudden change in speed differential.
Someone with a better understanding of physics might be able to inform us here, but I would expect that the maximum benefit from KERS on a straight would be obtained by using it to reach maximum speed faster, not to try to increase maximum speed (where a greater proportion of the power would be wasted fighting maximum air resistance, also, how would one optimise the ratio of 7th gear?). On that basis KERS is activated at lower speeds at times and places where blocking and braking zones are not in play, and we should be very surprised if there was ever a KERS-related crash.
Speaking of physics, just trying some back of the envelope calculations on what the adjustable wing needs to deliver: if we say it should deliver two car lengths in two seconds, that’s a differential of 5m/s or 18km/h. Well within what these guys should be capable of handling, but enough to go bang and probably enough to provide them with a excuse given that it will happen somewhat suddenly and can only be activated when the cars are in close proximity to one another. Allowing the trigger only at certain points means they’ll know when it’s coming, which in turn means it should be pretty obvious how each driver uses that knowledge. The ruthless types are certain to push the boundaries defending their positions, and I don’t think the stewards will be able to let it go given the risks involved in contact at 300+km/h. Either on or off the track, I reckon we’re in for some fireworks somewhere.