Which reninds me, I saw a video a few years ago which pitted a Dirt Devil Ultra MVP, a bypass machine, against a Royal upright. This prooved that not all bypass machines don't have airflow like a direct air machine.
BUT, it was only the case for the MVP. For those who understand the design of the cleaner, these results should not be surprising. This particular Dirt Devil has an unusually large intake bellow at the cleaner head. The passage up to the body of the machine is equally as large, and its not very long either. This allows for the Dirt Devil to be able to move more air. So in s nutshell, it combines a huge intake with the bypass vacuum suction power. Its incredibly effective, and there aren't any bypass cleaners that I know of that can achieve a result like the MVP had. I own an Utra MVP, so for those who don't believe me, I will gladly make a video that will demonstrate the capability of the airflow
This vacuum has, and I will compare it to an effective direct air machine if needed.