Thanks for that Mike! I still prefer using a separate upright vac to finish off a room being cleaned. I prefer to back out of a room starting from the area farthest from the door and uprights are better suited for that.
I just think that with the improvement in battery technology and the proliferation of more powerful cordless vacs and robot vacs, it's time to revolutionize the way power nozzle canisters provide power to the brush roll motors in their deep cleaning carpet nozzles. And new fancy lithium batteries would really do the trick.