At SpeakerCraft/Marcof we were building MTM arrays before Joe came out with his well deserved praise for his development. Joe was trying to eliminate lobing error independent of inter-driver phase relationships. Most of the time Joe used all 18db slopes and drivers that had a smooth transition in the mid band. I could speak extensively here, but If I read the ops starting message, I think the main question by the op is... Are larger speakers that incorporate an MTM design, inherently better in some way than other methods.
Done well, I would normally rather listen to a very good MTM over the same drivers in a 2 way design. However, when you step into large 3 way or 4 way well done speakers. I cannot say this is the case. Many large speakers sound quite good in dynamics, a large midrange transducer to have that extra air moving in the mid band, shoot, I've heard some pretty terrific 15 inch 2 ways. So for a direct answer, I would say no. The attributes that you mentioned are not necessarily better in an mtm over a non mtm in Large speakers. Legacy Aeris comes to mind as a great example.
Done well, I would normally rather listen to a very good MTM over the same drivers in a 2 way design. However, when you step into large 3 way or 4 way well done speakers. I cannot say this is the case. Many large speakers sound quite good in dynamics, a large midrange transducer to have that extra air moving in the mid band, shoot, I've heard some pretty terrific 15 inch 2 ways. So for a direct answer, I would say no. The attributes that you mentioned are not necessarily better in an mtm over a non mtm in Large speakers. Legacy Aeris comes to mind as a great example.