I like 15' because it's small enough that we can play with some cool effects, and also that there's lots of room to scale the range up at leveled intervals for a big boost in character effectiveness.
From a philosophical standpoint, I see the 15' as the effective area within which the Marshal can not only be heard, but anticipate and orchestrate events, which translates into what is essentially an aura effect. Other abilities, things that might be explained more as a single shouted command, could have longer ranges but effect less targets (perhaps just one), essentially trading power for distance.
I'm fine shifting the extra attack to a subclass. It fits with our rough sketch of what those might look like anyway.
From a philosophical standpoint, I see the 15' as the effective area within which the Marshal can not only be heard, but anticipate and orchestrate events, which translates into what is essentially an aura effect. Other abilities, things that might be explained more as a single shouted command, could have longer ranges but effect less targets (perhaps just one), essentially trading power for distance.
I'm fine shifting the extra attack to a subclass. It fits with our rough sketch of what those might look like anyway.