PRO-180-RPC-LRC as Center Channel?

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I'm building a new home and need advice on a center channel solution for TV in the Great Room.  Decision was made to not-have any floor standing speakers so plan is below.  Goal here is good quality music and have 5.1 surround.  The receiver is a Denon x4300h.  The room is 32' long x 20' wide x 13' tall (TV area on one half, Dining on the other).  One whole length of the 32' side is all glass, floor is polished concrete, so not the most friendly acoustical room.

 

Center Speaker: This seems to be the biggest challenge.  I'm ok with the in-wall grills on the L/R but  neither of us really care for the look of grill below the TV.  There's also the challenge of studs being only 16" apart, so I'm seriously given thought to a Center channel projecting down toward couches from the ceiling.  Both Triad and Klipsch have speakers that angle downward and have been proposed as "in-ceiling" center channels - attached is a placement recommendation from Klipsch.  Has anyone used this speaker in this capacity?  

 

L/R: These are in-wall, haven't made decision yet, my Home Automation Integrator reps and is suggesting Triad Speakers but there's no where I can demo them and I'm not sold on that option.   

Rears: Haven't picked these yet.

Sub: Will either do in-wall or in-ceiling.  I'm not too fond of in-ceiling since it's practically totally inaccessible.  On the other side of the TV wall is a kid's "attic/secret space" above the 9' line so I could put one (or two) up high on the wall and be able to access/replace in the future.

 

Framing is just about done, wiring to begin in ~ 2 weeks so I need to have my plan decided.  TIA for input.

 

PRO-180RPC-LCR-Placement-Recommendation.pdf