I actually believe that PD blowers are more efficient than vac motors because they don't "slip" like vacs do.
Porty makers give the unrealistic numbers when they rate their units.
For example a porty might have 200" of lift
AT 0 CFM of air...what good does that do.
They also will tell you that their unit will pull 300 cfm
AT almost no lift.
See they don't tell you the last part. When you rate them the same way that blowers are rated they will get like 75 CFM @ 12" Hg.
I would be willing to bet if somebody slapped a motor on a bane clene that needed 2 20amp cords it would whoop most other portys with its small blower.
Drew