You’ve asked several different questions, @coachpoconnor> (Were you really a coach?)
Your title asks about what share horns comprise of the high-end, and I doubt there are any definite sales figures for market segment (and how much does your definition of what constitutes a horn frame the answer), but I think it is safe to say that some horn systems, new, can be at the very top of the price tier if that’s how one evaluates the "high end." As you know if you’ve been around, there is a flavor of the month, and today’s "must have" becomes yesterday’s cast-off.
Aside from what constitutes a horn-- I think even what I own does not qualify without the upper bass being horn-loaded, you can run the gamut: from million dollar plus assemblages that are still incomplete, to very "one-off" projects that may have been a bit of DIY plus antiquarian. The interesting thing to me is the period immediately after WE-- though those components (both speakers and amps) are treated reverentially today, at the time they were not regarded as sufficient. Thus, the quest for better motion picture sound which took us to Shearer, James Lansing, and eventually Altec in the early days. There are lots of interesting parts-- how one puts them together in a horn based system is almost alchemy-- I think ideally, one would want the individual drivers to run their full range without complex crossover networks. Horn loaded mid-bass takes space. As does a horn loaded woofer (or two).
As to Klipsch, I have no current impressions. I had a friend in the ’70s with a period pair of K-horns, Marantz tube gear from the very early ’60s and it was fine. I think the innovations that Paul Klipsch is known for have been improved upon, modified and recast but I’m certainly not in a position to diss the company, its products or legacy.
I will suggest that very high sensitivity speakers will allow you to use SET tube amps, which can bring a magic of its own. That’s why I switched to a horn based system circa 2006 or so.
Now, I’m fascinated by the history and what some of these older designs can do. For example, you will pay top dollar today for a field coil speaker. At one time, that’s how the magnets were energized. Things improved enormously, but there’s still something "extra" a well tuned horn system, utilizing complementary equipment upstream, can deliver that is special. A sort of immediacy, plus dynamics, and no harshness (or the commonly ascribed attribute), "squawk." Have fun and good hunting. :)