Cathy,
I always thought of the "B" or Davis G as odd sized using full sized shuttle and bobbins and with it's own unique footprint and using Davis Long needles. I don't think calling it 3/4 size would hurt anything or ruffle many feathers as long as the needle, shuttle, bobbin, and footprint information goes with it. I used to have a "B" but passed it along due to difficulties in finding a cabinet or case for it and downsizing.
Jon