Question about matching front soundstage.

I currently have a 7.1 setup with 3x CMT-340 LCR (the LR speakers are on TP-24 pedestal stands and the center is horizontal below the TV) and 4x CBM-170 Surrounds.

I am moving into a new house soon with a dedicated theater room. I'm currently trying to brainstorm and plan out what I want to do with the room. My current plan is to build a faux wall with an acoustically transparent screen, and then have the LCR speakers hidden behind the screen. I also want to expand the system to a 7.2.4 Atmos system.

Having a front soundstage behind the screen gives you the opportunity to have 3 identical speakers for LCR instead of the normal setup where you have matching LR speakers and a different center. On that note, what I'd like to do is buy a single TP-24 pedastal for the center speaker and have all 3 LCR vertical. Are there any technical differences between the CMT-340 center and the mains, or is the center actually identical to the mains if you turn it vertical? Would I need to rotate a tweeter or something? Is it possible to special order a single pedestal or do they have to be ordered in pairs?

For Atmos speakers to go with my current system, is the recommended approach to mount 4 HTM-200s to the ceiling?

Also, if down the line I want to upgrade to a Sierra system I'd probably want to have 3 Sierra Towers for the LCR front soundstage. So a similar question: Is it possible to special order a single Sierra Tower, or do they have to be ordered in pairs?

Thanks.

First of all let me just say that I've enjoyed my Ascend Acoustics speakers (Sierra's across the front; 200s across the back) for nearly 3 years. They are to date the best speakers I have ever heard in a residential environment.

I believe the 340 center has a switch on the crossover for EXBAC that can be switched off for vertical use, but give Ascend a call to verify. Info on EXBAC below:

"EXBAC Defined: the front baffle of a loudspeaker creates diffraction losses as longer (lower frequency) sound waves travel along the surface of the front baffle rather then beam forward. This creates problems because these lower frequencies (usually located in the critical midrange response) are 6dB down from the higher frequencies which beam forward. Placing a loudspeaker on top of a TV amplifies these problems by effectively increasing the size of the front baffle, thus creating an effect where vocals can sound nasal and thin. Our EXBAC circuit actually compensates from these losses resulting in an incredibly clean and natural sounding midrange, even when the speaker is placed atop a TV."