Audi S5 4.2 Carbon build up issue?

Hi, had pretty much decided my new car was going to be S5 4.2. However googling issues shows up a major concern over carbon build up of FSI engines in general, but the 4.2 in particular. Mainly on US forms, so wondering if using high octane fuel in UK means less of an issue? Any owners out there care to share their thoughts?

Cheers

Well decided to get one anyway, so now have my first Audi after years of Merc, BMW, and Porche ownership. Fingers crossed!