Tom ... yes; the Model J is the square porcelain tubbed washer. They are "rare" in that Maytag stopped making them at the end of 1968; they weren't a popular seller. They were their "medium"-priced washer; the E was the most expensive, then the J and then the N. I think (don't quote me) the prices were in the early 1950's ... E = $179.95; J = $159.95; N = $139.95. All had the pump available and was an extra $10.
I, personally, really like the Model J. I like taking off the big square lid and having the whole area to work within. It has the same capacity as the Model E.
I don't "mind" changing water after every 2nd or 3rd load of clothing; I feel it's more sanitary that way and it depends on what is being washed.
I am one of those "young people", too, who were spoilt by having running water AND a water heater! I also have built-in tubs and don't mind changing rinse water all the time, either.
I usually always fill my Maytag's to the water line; they work more efficiently that way. The "goal" with these machines is that the clothes go through the water and not get dragged by the agitator. When I've washed partial loads with partial water in the machine, I don't get the same action as I do with a full load of water. Maytag always suggested you use a full tub of water; no matter how many clothes you had to wash. I always figure that if I have just a few things to wash and I want to use the wringer, there "has" to be a rug or something to wash at the end; then I don't have too much guilt for using all that water!!
The action is the same on all 3 models; it was a matter of personal choice. All 3 clean equally the same; I see no difference. I like using my Model N right now but maybe next week, I'll want to use the J or E; they all wash identical whether round or square.
Maytag sure produced a good washing machine when they made their wringers!!