I think you're missing the point. The topic is about 1 panel with 84 circuits. Yeah, it's essentially the same thing but in one package.
I think I would only use one if space was a big factor, or if it was much cheaper. I could see it getting very crowded. Someone mentioned using multiwire circuits to cut down on wires, but we don't use many mwbc's with the latest code change. I think residential is the best application for a panel that size.
We run multiple 1-1/4" EMT down under the floor, less than 24" long, to large (18x18x6) home run pull boxes. Since most of our circuits are 1-phase 1 neutral and 1 IG ground wire, we have ended up with as many as 252 wires (most #12, some #10) in the panels, all loads exiting down. Pretty crowded but if it's done really neatly (and we use wire markers on all 3 conductors per circuit to facilitate future removal/rewiring), it comes out very good looking.
Since the panels are so tall, you could also put the (Max. 23.5") EMT sleeve up thru a T-bar ceiling at 9 feet, for overhead load circuit.
One other plus--when pulling in future branch circuits, you are pulling into the large j-box, not into the panel with hot busses, then push the last 24" up into the panelboard. Jobs like this have all the later adds done energized.