does anyone know if the ACC in the 'sport' mode is stiffer or sharper etc than the standard GTI suspension?
is ACC in 'normal' standard GTI setting and 'sport' stiffer still?
Yes, that's correct.
Sport is almost too stiff for the crappy roads - too stiff as in you spend too much time fighting tha car and end up slower...but on the right road, the Sport setting makes the steering more responsive too, and brings the tail into play far more readily.
Comfort is epic in the wet for making quick progress with less understeer...and superb on potholed city streets or in icy conditions.
Normally, Dynamic is very similar to the standard steel dampers...
People say GTI is spot on Standard...it's good, but not great, when coming from a car with truly superb damping control - it's a compromise - like most cars...however, ACC gives you 3 modes on compromise which makes it 3 times less compromised in my book.
I only wish I could have the Sport steering, in all modes.