Would the need for 2-3 suggest one better replacement?
Depends on the application.
In one of my theatres, I have three flown in a cardioid array down-center between the two M1D arrays. In a jazz club that I'm working on, I'm going to have two of them hung from the ceiling in an end fire type array. The ceiling in the club is only about 7 1/2 feet high, and the stage is only 6" high. There's no other placement for them that's better, and we don't need huge chest thumping sub in the jazz club, just a little extra low end under the UPJ that will serve as the mains. And their compactness makes them perfect for this install since they are only a couple of inches taller than the UPJ when the Js are turned on their sides.
As in all things audio the answer is, "It depends on the application". In my case, I happen to work in spaces that don't do heavy metal, hip-hop, or EDM and don't need to make people shit their pants by pushing 17Hz at 130dB.