Can you elaborate on your last point, for those of us with puny vacuums? I'm intrigued as to why a more powerful vacuum would be worse for carpet, I assumed it would be better. What type of surface would need a 2kW, if not a carpet?
But seriously, I would use a medium-powered vaccum for loose debris on carpet. High suction in thin carpets can actually damaged them and for shaggy carpets it all depends on the design IMO (carpet mode), not the suction power. In fact high powered ones might be too close to the base and not suck the debris effectively.
I don't think using a reverse wind tunnel does any good to carpets, honestly.