samotronic - I think Miele may just be safeguarding themselves here.
The biggest expanse of carpet in my grandparents' house is in the living room, and it's a wool, looped-pile carpet, which they had fitted in the mid-1970s. Since then, it's been cleaned on a twice-weekly basis by their own succession of vacuum cleaners: a Hoover 825, a Hoover Junior 1346A, a Hoover Senior Ranger, and Hoover Turbopower 3 (can you tell we're a 'Hoover Family? lol).
However, for the past couple of years, I've been doing the vacuuming for my grandparents, since they're now in their 80s. I take over whichever of my cleaners I feel like using; their carpets are often the first to be cleaned with anything new - or old! - I've acquired. It's been Hoovered, Dysoned, Electroluxed, Maytagged, Sanitaired, Panasonicked, Seboed and Vaxed! Last Tuesday, it was 'Mieled' with my new S7, and I can honestly say I noticed no negative effect at all.
The only cleaner I would never, ever recommend using on this sort of carpeting is a Sebo, when fitted with its standard brush-roll. I made the mistake of trying out my Felix at my grandparents' house when I first bought it - it ripped chunks out of the pile, and the brush-roll was wrapped in carpet-fibres in seconds. Luckily it only damaged a very small patch before I saw what was happening, and shut it off.
Here's a photo of a small section of the carpet in question. It's still in near-perfect condition after nearly 30 years - so much for the Hoover being 'harsh' on carpets!!! Not for nothing did Hoover used to write on every cleaner, 'The Hoover makes carpets last longer'!
