Let's talk Tweeters!

The Heresy speakers were the only klipsch speakers I liked.  Just too small for my needs.  Also, the Dyn Esotar tweeters are pretty good as well.

I'm a horn guy well - for the entire frequency spectrum, that is (currently contemplating a tapped horn subwoofer to augment my main all-horn speakers, that would replace my well-integrated SVS SB16-Ultra) - and prefer horn-loaded compression drivers for tweeter duties. S.P. Tech's waveguide-loaded dome tweeters also sound very good (at one point I owned S.P. Tech's Timepiece model). 

I guess the sonic takeaway from this has to do with how the dome/diaphragm couples with the air "gradually" via the acoustic impedance transformer (the horn or waveguide), how the driver is effectively "relieved" through the horn/waveguide and hereby sporting much higher sensitivity to make for better headroom, dispersion characteristics that involves less early reflections, and not least that a bigger air radiation area is set in motion - one that far exceeds that of the dome/diaphragm itself. 

The cumulative outcome of this and how it's perceived sonically, to my ears, is a more relaxed/effortless, potentially more ingrained (with the midrange), and a more substance-filled, energized or "ignited" sound. It doesn't sound like a tweeter per se in the typical sense (and I believe there is one, a "typical sense"), and that's the whole point; focusing on high frequencies has a tendency of wanting them to "sound like something," almost like a distinct entity, but it comes at the cost coherency and of live, acoustic sound - again, to my ears. I once owned a pair of Raidho Ayra C1.1 speakers, and they sported the perhaps most enjoyable, delicate and intricate sound of the upper frequency span of any speaker I've owned, and as such I couldn't fault them. Ultimately though I found they lacked a real-ness here, which wasn't exclusive to the high frequencies. 

I find it largely fruitless to be brand-specific with tweeters. What matters is the principle and implementation. 

Kind of a related topic, that is using an "array" of tweeters, and midrange drivers as well, what some call a "line source", stacking the drivers vertically in the enclosure.

My brain tells me such a design would not have very good sound stage, that the "localization" of individual performers in the recording would be "all over the place", but the few times I've auditioned speakers like that, they generally have excellent sound stage.

It would seem to me to be a really expensive way to build a speaker.  With multiple drivers, would that offer the designer the option of using much cheaper drivers?

@ejr1953 - Yes, well designed arrays are pretty impressive. They have some of the same advantages of large ESL's without their limitations. 

Yes, some use relatively inexpensive "full range" drivers, and adjust them using DSP to make floor to ceiling arrays and they are pretty impressive.