Brian, from what I understand they used 2 rubber bands in the Lewyt copy of the Vibra Beat nozzle. So it stands to reason that the dirt would be able to pass through the nozzle better, thus resulting in better cleaning. As for whether Consumer Reports ever tested the Lewyt canisters in the 1960s after SCM bought the Lewyt name, let alone whether they tested the Lewyt copy of the Vibra Beat nozzle, hopefully someone sees this, has a copy of Consumer Reports from that era, and a Lewyt was tested. It would stand to reason the Lewyt copy would clean slightly better, for obvious reasons.
Aeoliandave - Dave Kerr from Stratford on here - has posted in the past some posters about the Lewyt Carpet Sweeper attachment from the early 1950s that would have been a optional attachment for the 2nd Lewyt tub canister that took a bag, the one that replaced the models 40 and 44 that infringed on the Filter Queen patents. I believe either Doug Smith or Dave Kerr may actually own one of these nozzles as well. I will see if I can find the thread on it later, and some photos. But I wholeheartedly agree with you - it IS a brilliant idea! A shame they didn't keep that design and Lewyt or other manufacturers slowly work on and improve it over time. In this day and age where we see homes of all kinds switching to hardwood floors and area rugs, the Lewyt Carpet Sweeper attachment would be perfect IF they could improve the brushing action and make it work better with each forward and back stroke. It would be a great addition to many cheap straight suction canisters, like the Simplicity Jill/Riccar Sunburst, Eureka Mighty Mite, Numatic Henry canisters, Miele C1 straight suction canisters, etc., and I would think greatly improve their performance compared to a airflow-robbing turbo brush.
As for Miele, yes they did try the Accu Nova battery powerhead, and from what I understand the main issue that made it bad was the battery pack not lasting long. Of course that isn't a issue years later, but the way I look at it is, the Lewyt Carpet Sweeper Attachment would take away the electronics that can go bad and do the job simply and effectively with little to wear down or break. Having said that, their limitation would be is that it would be most effective on low to medium pile carpets - on thicker rugs, full size battery powerheads like the Perfect Battery Powerhead and the battery powered version of the Wessel Werk EBK360 would be much more suited and ideal.