I'm trying to build a horizontal to fit better below the screen/tv. Not opposed to all chorus surround, but would rather have the ability to put a buffet-style unit below the screen. This center would sit on top of that buffet-style unit. I'm hoping to have exact matching tweeter/mid (and associated crossover components) and add a pair of ~95db 8 ohm woofers to emulate the ~98db 4ohm K48 that is in the Choruses (designing the woofer section of the crossover.) Tuning of the box can be done to 'match' the Chorus. I believe voicing is generally tied to the mid/tweeters and these will be identical.
I do know that there is an art to crossover design and interaction of box materials/construction can come into play. I have been designing/building speakers in hobby form for decades, so I'm comfortable with the required tweaking that will be needed to fine tune the center to match the Choruses. I have the appropriate equipment to measure/test the design and compare against the Chorus. I don't pretend to have a 'golden ear', but I've generally done alright with my other designs and the friends/family that have my other designs are happy with the results.
Worst case scenario, it will be a fun project and I would likely build a buffet-style piece and build in the enclosure for Heresy components and use that as the center. Generally, the forum seems to recommend using identical for LCR or suggest a Heresy for C duties. I know that some recommend Academy or other variants from throughout the Klipsch home theater offerings. Generally, I try to match all drivers in a HT configuration - Atmos throws a bit of a wrench into that with regards to old-school Klipsch (Heritage or 'extended' Heritage).