Really nice setup, Lynkage! As a gigging musician who has always owned my own PA gear. I recognized the SR Series cabinets the second I saw them. Way back in the Nineties I had a band and we pretty much used JBL SR cabs and subs, powered by Crown amps, exclusively. Crown and JBL is my favorite sound reinforcement combination, hands down! I also really like the fact that you opted to go passive over active. But that is personal taste since active enclosures have come a very long way since the Nineties, and even a great many sound engineers have started to prefer active. However, for those old Nineties JBL speakers, there is no comparison between passive and active, if you are going to be using sound reinforcement from that era.
The only niggle I have is that I have never been a fan of 15" drivers for the woofers when pairing with 18" Subs. Whenever I built a PA system it was always a struggle to decide where my lows and mids were coming from, and to be honest, I think that there is way too much overlap between 15" woofers and 18" subs, and it can leave the coverage between the high midrange and low tweeter a little sparse.
My rule of thumb is if I am not going to use subs at all, then I have to get the tops with a 15" driver, since otherwise the really low bass registers won't be covered well at all. But if I am going to use subs, the 12" woofers sound a lot better for the upper mids and there is little or no overlap between woofers and subs. In my band back in the nineties, we used the SR4732 speakers instead of the SR4733a. At some point, you may want to see what your system sounds like with 12" woofer drivers instead of the 15".
I know plenty of bands who have tops with 15" woofers and they are all right if the band doesn't always use subs. Meaning that if they are playing small clubs and decide not to use subs that night, then the 15" drivers sound better. So my rule of thumb with sound is that if I am going to either never use subs or only "sometimes" use subs, then I will settle for the 15" drivers, even though I am not happy with how 15" speakers do upper midrange. Its a compromise however you look at it, I guess. But in a configuration like yours, where you have built in subs and there is no issue of whether or not you will be using subs for a particular night, I think you would like the sound of the 12" drivers much better when paired with your subs.
By the way, you or your guests may not even notice the difference or care. But since you have obviously put a HUGE effort into your theater, I think its worth considering 12" drivers for better upper midrange coverage.
Of course, since you seem to be always evolving your theater, if you ever decide to do so again, and you want a front end with even better sound and an even smaller foorptint, at some point, you may even want to consider upgrading to JBL's VRX line. With the more modern tech, you don't have to worry so much about going all passive anymore, since JBL has really pioneered the concept of building amps and speakers in active boxes to be engineered specifically for one another. Back when those SR's were in their heyday, active cabinets consisted of companies basically mounting their speaker(s) in a box, tossing in any old powerful amp, wiring them together, and that was that. So passive was the ONLY way to go back then. Active sucked, particularly for bias and crossover points and the active speakers just never sounded anywhere near as good as a properly configured passive system.
Now, the better companies like JBL are actually engineering and biasing their amps and speakers to work perfectly together and are doing incredible work with crossover frequencies. JBL uses high quality Crown amps in their active cabs now, and the sound is phenomenal. But if you still wanted to stay old school, VRX has passive boxes, too.