I can echo a lot of what Magic-Clean and Gansky said...
In the mid to late 1970s, more than 900 homes were built in the neighborhood I lived in in Denver. The builder predominantly used two kitched arrangements, all GE, one with double in the wall 27-inch ovens, and the other with the two oven HI-LO range.
I think some neighbors who had the hi-lo said the same that access to the rear elements on the range top was a bit annoying, but that the top oven was well sized, and very convenient. Its smaller size made it preheat quickly and it likely used less energy than heating the lower full-size oven. The top oven was not as well insulated however, since it wasn't self cleaning, or so it seemed anyway.
I'd love to have one of these, in fact several years ago I remember a new one being posted on here, never used. I almost went for it.
My aunt and uncle in Florida have one of these. They had a fire in the wiring on theirs a few years ago, which led to a kitchen remodel. Their insurance company had a heck of a time finding another of these for them, but they eventually did. So, they repaired and updated the kitchen, but installed all this around another hi-lo. I don't know if it was NOS or just a clean used one.
G