to me, the real point of diminishing returns in Speakers starts somewhere around $1250 per Tower ($2500 per pair). When I was shopping, the best Speakers I heard were right in that neighborhood, and the more expensive ones were not so much better in SQ to make me question whether I should stretch further.
This is not to say it is not possible... just for me, this was the point where I started seeing the disconnect in cost vs performance.
Before I started stretching my budget to get the best performance per dollar I could, I was shopping much lower in the food chain, and there is nothing wrong with that. There are a lot of quality Speakers out there, but what I found in comparitive analysis is that you can always very easily ask the question, "why not spend another $100 here to get this, or $200 there to get that?"
And this comes back to the tradeoffs in design that all Speakers have in common. Size, Extension, Sensitivity: what are the goals the designer/manufacturer are working with for a particular product or line-up; what are they trying to deliver to the market; and how much can they charge for it against their cost to develop and build?
If you take the time to read reviews and compare similar product from different manufacturers, you will likely find these small details where one subjective reviewer may say Speaker A is a little more clear than Speaker B in the Mids, but Speaker B is stronger down low.
I did this for a lot of Speakers, reading everything, sorting past the subjective cr@p, and trying to develop my own understanding of the vocabulary the writers were using. Mind, this is way, WAY different than watching BS YT influencers wax prophetic about Speakers without really telling you anything other than they liked it, which frankly they do to just about every product that crosses their threshold.
But after reading all that stuff, then going out and listening to some of it, I started to understand some of that vocabulary, and some of the things I read made some sense... I was able to translate their 'speak' to my experience, and in the process better understand some of the things I could expect.
Now to fit that in to your question, the catch is is the specialization of what a designer is questing for, and what they can do and sell. For guys like Jeff at JTR, or Dennis Murphy or Jim Salk, this is a little different than bigger companies like SVS, or anything under the Harman (JBL, Revel, etc) or SU (Polk, DT, etc) umbrellas.
Jeff is using very high end coaxial driver in his horn, and they aren't cheap. This would likely compare more to the higher-end and more elusive JBL Synthesis Speakers more than they do to the JBL Synthesis HDI which are really their introductory models in that market segment. The HDIs are a step or two better than the Studio 5 series. Neither are likely directly comparable to the JTRs.
On the other hand, consider something like the JBL S4700 retailing somewhere around $15K per pair and compare that to the Noesis 215RTs.
www.jblsynthesis.com
As the consumer, you are obviously limited in some manner by what you can afford/may afford/are willing to stretch to afford...
...but that is a limit that is only really dependent on you and your choices. I saved for several years to originally buy a new Tenor Sax, only to realize that that wouldn't make me pick up my horn again and work it out daily like I used to. I changed my plan and took that money and put it towards Audio, saving up everything I could spare for another year to be able to afford my rig, no holds barred, and without going into debt for it.
So when you decide your budget, and what you are willing to spend, I also urge considering whether you are buying out of want, something new to satisfy an urge; or are you buying for a system you can enjoy for 5-10 yrs? If the former, and upgrading in 2-3 years, maybe it doesn't matter. But if you are choosing something to last you 10 yrs, well, that's why I looked at the minute details I described above.
I know you've laid out some options, you've considered your budget and usage. What is your hang up at this point? (Not asking to be snarky!
) But I can see it in your process, and I was no different until I heard the Philharmonics I now own. I can tell something is still hanging and keeping you from committing.
What's the scoop?