I remember reading years ago, that the Dyson Digital Motor was supposedly able to operate with no exhaust filter, 'cos there were no carbon dust emissions. That is believable, because it is a brushless motor.
If the Cinetic cyclone technology is so good that a pre-motor filter is not required, why on Earth did Dyson not fit a Digital Motor?
Had they done so, there would be no pre-filter and no need for an exhaust filter, making the machine almost filter-less (that mesh screen in the bin is still a filter).
Maybe they need the exhaust filter to reduce noise levels...