The ELAC Debut 2.0 is significantly better than decent. Don't be fooled by the price.
I'm just trying to direct you to what I suspect will help with the dialog issue.
You're over thinking it. There are voices in music too, and voices in movies aren't limited to the center. A good speaker is a good speaker. You want the speakers, especially the front three, to blend together as seamlessly as possible. Ideally, that means three speakers from the same...
There are definitely disadvantages to having one in front of the other. That's a solution for car use, mostly, where size and cost are most important. The concentric design was developed entirely for the purpose of creating a more "point source" speaker. Phase coherence, off-axis sound...
BTW, if you really want to get into the technical weeds, coaxial and concentric drivers aren't the same thing. Car speakers often have coaxial drivers, which is a tweeter in front of a mid/bass driver. Concentric drivers are one physical unit, with dual drivers. A cone and a dome. When...
...that too.
With some movies, especially action movies, the sound effects can overwhelm the dialog. Also, the surround channels could be calibrated too high, which makes dialog hard to hear during action scenes.
It's true that 2-way speakers crossover in the 2KHz area, which is the center of dialog, but 3-way speakers also tend to crossover in the same area.
First, I would increase the volume of the center speaker. Go into the speaker setup and then channel levels, or something like that. You'll...