An interesting thread. Glad to see you back posting after a (rather long) pause, Barry.
It sounds as though GE had among the best disposers back in the 1960s and 1970s. Really, it is a shame they let the production go to pots after all those years, having established such a positive brand reputation.
Unfortunately, I can't make much more of a meaningful contribution on this thread, as disposers are practically unheard of in Australia. Brand-new, they command prices that most home-owners simply cannot justify. This, combined with the fact Australians have been led to believe they are a waste of energy, increase burden on the sewerage system AND apparently clog drains have all contributed to this "stalemate" of sorts.
With regards to the person who cannot use a disposer with a septic tank, I wonder if perhaps there are means of running the kitchen's drain to a composting unit, which allows drainage into the garden, but with a fine screen to capture kitchen scraps and compost them?
It is unfortunate the disposer works so well as to circumvent the septic system altogether; all those food scraps would be wonderfully beneficial for the microbial life that exists in such a system and would certainly balance out the problems associated with using harsh(er) cleaners for the bathroom and toilet.