Why 3 Tweeter?

I agree with the above, and though I am not familiar with any reasoning given by the two companies you mention, I believe in other cases like with Dynaudio, a second tweeter was employed but rolled off before it got into lobing frequency, much like the second woofer in a 2.5 way. Just like the woofer example, with a second woofer just helping out in the bass frequencies but not interfering in the mids, I think the additional tweeters are designed to provide support near the crossover point, especially when that point is at or under around 1,500 Hz, so that as you push a tweeter lower, then a second or third tweeter is ready to share the load and help lower distortion and improve dynamic range at those frequencies near the crossover point. it is also my understanding that the additional tweeters could not only be rolled off before getting up around lobing frequency (around 3-5kHz depending on c-t-c distance), but could also be shelved down entirely by 2 or 3 dB, which would also mitigate their ability to distract from the imaging specificity we would expect from a single tweeter.... no expert on this, but something about our natural reflex to cue in on the louder source and that perhaps that makes the phase issues less likely to be noticed..who knows...