The Lindhaus is a very effective cleaner...
Lindhaus does all of their comparisons after all the vacuum cleaners have been in steady operation for 10 minutes. The fans are pulling air through a carpet, the belts are warmed up and expanded, the machine is in real life operation mode. The airflow is measured as the vacuum is in use. Lindhaus knows people vacuum too quickly, too infrequently, and improperly. They design their machines to operate at maximum dirt removing capability under the real life conditions of their use.
It would take too long to type all the info Cliff shared with me about vacuum cleaner design, suffice it to say, someone who thought he knew a lot learned a whole lot more.