With the canister vacuums strong suction is needed to maintain the airflow through the hose.
Direct motor (dirty air) vacuums don't need a lot of suction if (when) the piping is extremely simple and in the most cases large diameter.
One thing what I find very frustrating is using the low airflow vacuum on the bare floors. There is no brushroll helping in the pick up.
For example: Using the hard floor nozzle or just the pipe end in the tight places.
High airflow vacuum sucks up dirt from further away and with the low airflow vacuum I really need to see more effort to get the job done.
Vacuuming is faster with the high airflow vacuum.
So suction is needed to maintain the airflow.
Airflow is the important part what does the job.
Here is what I mean:
[MEDIA=youtube]zZKbEmm_t4Y[/MEDIA]
