Well, let's start with looking in depth to the wear action of a classic clutch, before we extrapolate it to the automated dual clutch action:so the RPM falls when the friction is removed..... Gotcha
Can you articulate the mechanism that engages the clutch as the ECU sees a commanded throttle position opening above idle? Also, how much clutch engagement is being commanded when in gear, brake hold engaged?
It would seem that there would be more effective clutch control, than introducing an eco stop feature, but I am often naive
There's a category of manual gearbox drivers, which some affectionally call clutch-raiders.
What does a clutch raider do?
A newbie will semi-slip the clutch all the time and cause premature wear, polishing of the friction areas and heat that will in time kill the throw-out bearing causing bearing chatter in neutral.
An experienced, intent clutch rider, will just not yank the shifter to neutral. He will step on that clutch early on, as the traffic slows down in a traffic jam, and keep the pedal stepped all the way down. He will not semi slip the clutch, he will let the car free-wheel in the traffic jam, only gingerly tapping the brake to adjust the speed of the car, to what the others are doing.
Some will even wait every single traffic light, with the transmission engaged in first gear, with the clutch stepped to the floor.
What kind of wear do these guys cause?
Well, the throw-out bearing will be spending a lot more time pressed against the diaphragm of the clutch plate. This will definitely speed up the wear of the throw-out bearing.
Also, the teeth of the clutch diaphragm of the clutch plate, of such a clutch rider, end up with deep wear rings, around where the bearing sits on them and it can be (seen it in Europe), as bad as the bearing literally starting to cut the teeth off of the diaphragm of the clutch plate, before the clutch disc is worn.
And of course this generates extra heat.
In time, the clutch of a clutch rider's car, starts to deactivate. Those teeth become less elastic and cannot completely disengage the clutch disc. So the gear changes become grabby and crunchy.
Honestly, I think the dual clutch tends to want to act like a clutch rider person. There is no torque converter, to allow the car to sit without wear with the gear engaged. This means that the clutch deactivation mechanism remains engaged as long as the car is not in neutral.
You saw that when you bring the car in neutral, the revs drop to the same point be it in comfort or sport+. To me this means that the clutch is deactivated.
Now, if you ask me exactly which parts are going to wear with this scenario in the dual clutch gearbox, I have to research a bit. It won't necessarily be the discs themselves, but it will be one or another clutch activation component, and I would think the associated clutch bearing.