I read this with real interest. I have an 06 A8 diesel. To be fair it's got all the toys thanks to the previous owner. When I had it serviced the local Audi independant specialist loaned me his 07 plate S4. Decent of him I know BUT the difference in car was staggering.
The S4 went like the wind and sounded great....and did 18mpg
....but the overall feel was not a patch on my own A8, from the seating, the dashboard, the build was even different quality. I had the A8 remapped and it won't compete with an S4, nor am I suggesting it will - but as a family saloon that ticks many other boxes - it's nippy enough.
I guess the issue is that even if a car is a few years old....in it's day it was a high price range topper and tbh that doesn't alter, gadget and electronics do and there is the key difference....
so to compare a new A5 to an old S8....I would go with an older S8 all day long...
I used to have Ford RS's....I have the same thoughts over the 'softening' of that badge too...and the introduction of the ST range....the Audi S cars should be special, not sure we all need a nuclear explosion at the rear each time we change gear.....Walter Rohrl may disagree !!