I was planning to go 3way with the modular speakers and have separate powered subs for LF extension and SPLs.
If you are going to have subs for the last octave or so then you should let the main speaker be more resolving ( in my view). The SEAS Excel drivers are good at this the Peridot Excel might be configured into a 2 or 3 box system. The other option is the Tempesta set. If you need a bit more sensitivity the Extreme. Which is a 2 box system.
In my systems the Peridot Excel is supported by a TC Sounds 15" in the front and a smaller SEAS L26ROY in the rear. The room is 12 x 30. My Tempesta Extreme will be supported by a TC sounds. 12" in a 15x17 room.