I agree on the value of wide band mid-rangers I looked at several options and eventually had to compromise on the lower end with the Domes. Crossing in the middle of the speech range is not good for sound. We really want our best sound there not our worst. I wonder if adding a low end support driver to the center would get better sound.
I guess it depends on how loud you want to play it. In this system I can play it as loud as I dare, in a condo with shared walls and never a moment of distress. Crossover to the subs is at 90 Hz for this center, which is optimal for this driver in a sealed box.
Now in my lines for my Grand Forks Studio I used four each side as a line source in 1976. I had them bi-amped at 400 HZ. There was never a problem with spl. However I have never been fond of line sources under domestic conditions.
For auditorium use 8 or 16 a side as a line source biamped to 15" drivers in enormous back loaded horns crossed at 400 Hz, gave by far the best auditorium sound I have ever heard.
The really surprising thing about those drivers though is that in a TL, the bass is very good and surprisingly deep, and for spl compares very favorably with the Quad ESL 57 of that era, which these modules were designed to compete with. In terms of bass, with TL loading they bested the ESL. I listed to a pair of single driver TLs with those modules for many years very happily.