With an acoustically transparent screen, you can place your three front in-wall speakers in the ideal locations.
The original intention was to always have three identical speakers up front. The whole horizontal center speaker was always a compromise (and a fairly major one at that) in order to accommodate regular television displays in the home that would not allow for a center that is identical to the front L/R speakers. With your acoustically transparent screen, you can get back to the ideal design - with three identical speakers - all of them vertical with their tweeters at ear level.
The "aim-able" tweeters are a horrible marketing gimmick, IMO. By rotating the tweeter, but not the enclosure, you are creating massive diffraction problems and ruining the dispersion of your tweeter. Stick to a speaker that has fixed driver positions. I get the intuitive idea of aiming the tweeter, but when you measure the output and see how it destroys the sound quality, you'll understand that it's all marketing and zero science. Speakercraft is one of my most hated speaker companies. Their products are insanely over-priced. Custom installers love them because they cannot be purchased in stores or on the internet. They are strictly available through customer installers and they are the rip-off to end all rip-offs in my book.
Obviously, your center speaker goes dead center - vertical whenever possible and with the tweeter at ear level. The front L/R speakers have a range of acceptable angles. In many music-only systems, people prefer a wide position with the speakers 30 degree to either side of center - creating an equilateral triangle with the front L/R speakers and the seating position as the three points of the triangle.
For movies, the standard is to have the speakers closer together so that they are closer to the edges of the screen. THX recommends that the front L/R speakers be 22.5 degrees to either side of center. So, in general, for movies, you want your front L/R speakers to basically flank the screen so that sound cues follow the action on screen. And that will typically put them somewhere from around 20 to 30 degree to either side of center. Again, they will be vertical with the tweeters at ear level.
The RBH are a fantastic choice. When we talked about this in a previous thread, I also recommended the Paradigm Signature in-walls and I still do. But the RBH in-walls that you're considering are excellent and there is no real reason for you to worry about their quality or that you should be looking for something significantly better.
Any speaker should have at least 2 feet or more distance from the side wall (except for on-wall surround speakers, of course). That shouldn't be any problem for you is you stick to the THX or Dolby speaker placement guidelines
Best of luck!