Very cool. The DCM TW/TF are on my "must hear" list -- have always wanted to check them out but haven't had the chance.
It looks like you have it set up for a phantom center channel.
Not really. I have tried a number of speakers in that position.
Tried some DIY JBL pieces years ago when I had JBL 4341 Studio monitor as mains. Tried the Vandersteen VCC-1 center, (2008 - when I ran Vandy mains & sides),
and I've tried a DCM Time Piece (circa 2012 with DCM fronts, sides & rears).
The tonality just wasn't a good match with any of them - and thats the trick - matching the tonality across the room.
Now the UREI Studio Monitors with JBL coax drivers give us the best sound of everything I've tried so far, and they were basically unknowns when I bought them (2 pair)
I do have an 3rd pair of spare coaxial drivers but don't have room under the TV for a UREI coaxial as Center there.
So I have a contemporary JBL center speaker now - had to go look for the model #. Its a Studio 520c, affordable, its ok but nothing special ...

JBL horn & slot tweeter w/crossover circa 2006

Vandersteen system, prob 2012

DCM TimePiece as center circa 2014

JBL Studio 520c now