Well, that's nature of S/S in a way. It doesn't work, when engine needs more power for some reason, shouldn't work after spirited driving, to allow turbo to cool down, and doesn't work when A/C needs to cool down the interior. Anyway i can see, that in O4 to works more often than in Ateca and Leon. But S/S will never work 100% of the time, even in "full" hybrid.
Yes, that was annoying. One of the reasons i have almost always disabled it in Ateca.
But in O4, which is mHEV, this is not an issue for me. Engine start is so fast, and drive aided by electric motor-generator), that i cannot see a difference between this, or having engine running all the time. I mean situation where i'm slowing down, engine shuts off, and before i stop i'm accelerating again. In O4 reaction to accelerator is instant.
Yes, there is, but it barely noticable for me. Or maybe i will put it another way - some vibration is there, but it's not annoying for me
Combining it with a fact, that - again - reaction to accelerator is instant, it have no issue with this at all. In fact i very much like S/S in this car