I just thought to share this test.
Results were very surprising. New vacuums didn't shine in this test.
Lux Royal D790 from the mid 90's was the best.
Philips P74 very close behind. It's from the mid 80's!
Shark Rotator Pro Lift-Away was last.
Electrolux UltraFlex with the new 2100W motor (yes I have changed the motor) could'n cope with the Lux Royal.
UltraFlex seems to have the best suction, but I think that Airflow is more important.
Results were something that I really didn't expect.