Even though in someways the Big Trucks are over-rated, I still voted No.
They do the job they were designed to do and do it very well. They were meant for high production, dual wanding.
There are too many guys posting about how well they are cleaning to dismiss it.
However, if its an owner/operator cleaning mainly normal residential, I think they are over-rated. With the new tweaks in the industry, even my little 25hp Kohler with a 4HT and water at 200F gets the carpet clean and dry within a couple hours.
As for the billboard, that works because everyone is used to vans. But thats all it is, just a bigger box. I got those same comments about being such a powerful truck when I ran what everyone called my POS Big Red, because it was in a "different" box. People wondered what was in there. Put that same unit in an even bigger truck, give it a few tweaks, and its the same as the orig V, just a slide in rather than PTO.