lux1521: PLEASE! If you get a chance, I'd really LOVE to see the rest of the booklet, it looks fascinating! I'd appreciate it so much if you were able to post it
I'm not nearly as knowledgable as Stan Kann, but I'm positive the 543 and 700 were sister models: The 541 was renumbered as 543, given the Agitator brushroll, the new duventine bag, and was sold as the cheaper alternative to the Model 700. I have several scans of adverts of the time showing this, but unfortunately, they're on my other computer, so I can't post them at the moment. Don't want to hi-jack this thread either!
I have a 543, and it really does struggle to cope with the Agitator, it takes maybe 10 seconds to get up to full speed. It's whisper quiet, though - I have a video of mine in use on youtube (see link below), and it really is as quiet as it sounds. Seamus can confirm this, it was one of the ones we played with when he came to visit recently! When you've watched the 543 clip, watch one of the others for sound comparison!
It's not a terribly effective cleaner, more a carpet-sweeper with suction! Does ok with surface litter, but I doubt it's getting much deeply-embedded dirt out!