Concerning dynamics; the sense of dynamics is often related to frequency response in my experience. A rising trend in the highs comes off as more dynamic regardless of horns or not. And distortion and compression can also subjectively give increased sense of dynamics. Of course, there's other "tricks" as well, like limited dispersion and arrival time of frequencies. Higher directivity gives higher SN ratio and early arrival of the high frequencies gives a smack to the highs - at the cost of coherency of soundstage and warmth. (Personal opinion based on testing).
Ever heard the phrase "Klipsch is very dynamic"? Well, I was mighty surprised when all that dynamics went away as soon as I used EQ to flatten the extreme rising response from 2-10 khz in the cute little RP-160m I had. Lesson learned and now I can easily demonstrate that my M2's can change from highly dynamic to soft pudding by changing the frequency response of the tweeter.
I'm willing to bet
@MKR 's good name that the reason you see many of the horn speakers from Klipsch and JBL with a rising trend is because they live and die for the reputation of perceived dynamics.
All very high capacity speakers with neutral response I've heard have had the same trait, shocking the shit out of me when I turn to talk only to realize the volume is way higher than I thought. If it sounds very loud when it's not, it's likely you have either shit acoustics or distorting/compressing drivers.