Klipsch Heritage Range

The IV sound more open.  A little less forward.  I think the new mid driver is much better than the III driver , very detailed.   Vocals are much more intelligible.   Tweeter / Mid coherence is improved

I did not spend much time with the III.   They were unavailable so I just left a deposit to secure my trade on the IVs and they called me when they arrived ..... I bought the IV sight unseen.

@jwl244

Strange. 
Which speaker/speakers did you compare with?
Which amp did you use? 

I got the Heresy-IVs back in late November. When I started to go down the path of picking a new speaker, I had another speaker maker point out some of the issues with my room so I planned to treat the room around the same time that I ordered my IVs. The Heresy's came, and I had some of the same experience as @jwl244. 

Then I started to treat the room - I added diffusers on the ceiling spaced out between the speakers and the listening position. I added some diffusers to the front wall. I move the carpet. I replaced some flimsy window coverings with thicker, dual cell blinds. I added some art to the walls. Everything changed. I made a few other, small changes, moving some of my better (more neutral) cables back into the core system. 

Then, I really spent time positioning them. The difference between when I first put them in to now has been remarkable. I liked them at first but felt really unsettled about them. Now, I just really really like them to the point where I forget they are there and just find myself fascinated by the quality of the music. The ceiling diffusers moved the sound stage up, positioning made it wider and more engaging. 

I still have my LS50s - they scratch a different itch. And, like one of the other posters, I ordered a Decware a week or so after the IVs and in a few months will get to play around with that. I find that the IVs have done exceptionally well with the currently playing LTA Z40 (but what wouldn't), the Schiit Ragnarock, and the Rogue Sphinx. The Sphinx and Heresy combo is a little noisy for my taste, though, when nothing is playing. 

Music - a little of everything but not so much classical. Nick Cave's new 'Litanies' is playing in the background as I type this, and it sounds magical. 

Hmm... so maybe it basically a room issue. But still, I have never heard any fan of classical music saying they have a Klipsch speaker from the Heritage range.

@simna and @leahy 
I first tried a combination of the cxn v2 and Cambridge audio cxa81. Then I tried with my naim uniti atom. I eventually wound up keeping a pair of Martin kogan 6xti. Leahy I didn't burn in as you are suggesting. They were new.