Hmm, if the Rainbow did almost as well as the Tristar, despite much worse airflow, that suggests that its power nozzle is pretty good - that, or the Tristar's is fairly bad. I'd be quite curious how the Silver King compares to the Patriot (both with EBK340 nozzles, it looks like), or how the various Filter Queen power nozzles compare to each other.
IIRC, the FQ 75th Anniversary model still has the two-stage Ametek motor, right?
