A:Answer The "motor" power has very little to do with the efficiency of a vacuum.
The efficiency of a vacuum is measured in AirWatts, a relation between electrical power used, flow and suction. It's a bit like MPG for a car.
You could have a vacuum with great flow (aka a fan) and very little suction, or the opposite great suction, low flow. (aka a vacuum pump), that would not help you much.
In the same relation, if your vacuum was using 5,000 Watts and generating only 250 Airwatts, it would be a very poor vacuum.
Airwatt are measured at the baseplate, and not with all attachments.
Manufacturers that do NOT publish their Airwatts have something to hide. ;-)
The Airwatt measurement is based on ASTM F558 F17 Just in case you want to know ...