Why not more OB designs. You have mainstream speaker companies that have built and rebuilt box speakers, new parts, and new drives that is all they do and it is what their buyers expect, so to go to open baffle they would lose a lot of customers who like their "sound" of their designs and the myth still spread around that OB designs cannot do bass.
I look at it this way. Would Clayton go to box speakers? I doubt it, he loses customers, plus OB is his design and truly what he believes is better than a box speaker design.
Electrostatic speakers are also a nitch speaker in themselves. The Quad speakers 57's & 63"s I absolutely love. Yet I enjoy my sapphires M3's in some ways, even more, do I hear such trade-offs, yes Quads project the performance and size and depth of the recordings, tone-wise each instrument is one unto itself, it's hard to put it into words what they do so well, yet my M3's sapphires can give me 80% of the best the Quads can do but now with unlimited dynamics and deeper bottom with dynamics, though the Quads can hit low 30's in a well-treated room you have to watch the volume levels so you don't arc the speakers. I owned the Quads for 10 years, before that Dynaudio Confidence 5's, Legacy Audio Focus, ProAc, Dalquist DQ10 (open baffle design) woofers was a boxed design. All of these speakers I enjoyed, all sounded different, all good, and over that time I heard, many other main brands pushed over, and over in magazines that sounded like crap, unlike those listed above. That the Spatial designs can be so good at such high-end values and affordable to many in this hobby says a lot about the design of them, and Clayton at least is making products that many can afford and a speaker that any good amp can drive well.
What is best to use with them is only the gear we/I think sounds right, I could buy 10 preamps, amps, DAC whatever, and insert them in and out and go nuts in the process because, in the end, it is not that one is better its the one my ear says I like and like tube rolling a big chance I like something of each design and miss that be then gain something in another design or tube switch.
I have made changes for change sakes over the many years and what I did learn after a while is good, nothing is jaw-dropping better, and what impressed me right out of the box usually I will be returning within a week, they fatigued me, the old hi-fi sound not music sound. With the way music is recorded today, the major labels not looking to audiophiles as their buyers but the 99% of the consumers many of the speakers I owned would never show how good they are with such over-processed music which sounds great over a Phone, pair of beat earbuds, or stream which is the #1 trend today. If you want to hear how good the Spatial then feed them recordings that were recorded well with care given to sound quality as close they could sound natural in color, tone, depth, weight, and presence, as the producer could, from the masters back in the day. A friend brought over a current Jazz recording, It sounds OK, but flat, no feel to it, just perfect little sound of instruments playing, compressed like most music today so they sound good on earbuds, etc. I played a mono 50's Jazz recording for him, and he sat there and after a few minutes said wow does that sound real like they are in the room, I can see now why you like these speakers, I never would have to know how good these are paying my music on them. Nuff said how important the recordings are to what we say sounds real vs. sound.
So be it Vinyl CDs or streaming, what you feed your gear and speakers can make or break your system and gear and chasing your tail on hoping the next DAC, tonearm, cartridge, or CD/DAC players will make inferior recordings sound better just is not going to happen, in this day in time, when music can now be recorded at home, on a PC and mixed, where musicians can lay their track down from their part of the world and then digitally send to the producer to mix them as he sees fit, is what you are going to hear on our systems and the better the speakers and gear the more you will hear how really far they are from sounding like real instruments, vocals and the in your room presence with air and depth if it's not there, to begin with, no room correction DSP correction will change that.
It is not what the producers ever intended nor what the buying public needs, if it sounds great on my kids' buds, radio, or streaming radio that is all that matters, and where the compression works its wonders, it makes music sound great on those devices, we philes are not on their radar, we are not even a thought. Back in the early 60's they made stereo recordings that were horrible, I called them special effects cause they were made to impress buyers of the 2-channel stereo sound, so they made it extreme with no thought of imaging and naturalness at all, of course, you had a lot of good stereo recordings also, RCA Living Stereo set the standard, DECCA, AudioPhon, Gramaphone, Columbia, Reprise, and of course the Mercury Living Presence and Capital records in the '50s
Classical is the last form that they have to record in a concert hall or studio together, and those sales are at an all-time low. In my own experience, I could never judge a speaker's value with such recordings, and yes, my kid's music does sound great on his buds from his cell phone, just a perfect match for low quality mastered music the compression sounds great on these portable listening devices, my kid loves it and that is all that matters to him, so he is one happy camper, we could learn from him enjoy the music, know that nothing is perfect and it is all a different with some trade-offs from gear to gear, speaker to speaker, and power cords used.
This is my 47th year in this hobby, and I am still enjoying it, but my tail has stopped chasing itself for the most part, though my one weakness is how power cords can make such an impact on one's system as a change of gear can and its a lot cheaper to boot..smile! I find their impact fascinating more so than interconnects, speaker cables can make a good impact also from top to bottom of the speaker range.
Enjoy your systems for what they are, but it is the music that should be the focus and worrying if something can always be better, different, yes, but better is only to our own tastes and what our ears like. I just heard a PS Audio DirectStream DAC and it was as good as any I heard, not even sure what the PS Audio DAC rates online word of mouth, but in one way better, it made streaming and discs sound more musical, toe-tapping, enjoyable, and while keeping body and weight to the music, If I was buying a DAC and I am not, that be a good choice with my speakers because it made music emotional not just clean, dynamics in your face and wow factor, no it failed there, but it sounded like real music, natural ebb, and flow, not in your face impressive until you get what the PS DAC was doing so right if you are used to natural well-recorded music.
Holo I heard, Denafrips, Tandor, and I take the PS for the money over any of them to my ear and how I feel music should sound from my 47 years of listening in all formats over that time frame, and recordings over that time and how they have changed as technology that could be used in the studio to present music in there own way. If you like it, that is #1 for me and it's personal, as it is for you I am sure. Our individual systems please us. Enjoy the music!