I have many hours listening to the RM30s w/CDWG since I worked the VMPS room at CES.
They amazed me and were significantly better than the "prototypes" I (as a dealer) had been playing with.
While I have never found a limited "sweet spot" an issue for the serious listener, the CDWG does more than just create a "Soundstage" that is not dependant on sitting equidistant between the speakers.
It creates a smoothness of frequencies (from top to bottom) that make sound resemble reality more accurately.
In the real world, frequencies are not divided amongst multiple drivers from different locations. Sounds are also not "crossed over" to these drivers creating various anomalies.
The CDWG has a tendency to more accuratly "smooth" and "shape" these sounds to sound natural from most any room position.
This not only gives you a "soundstage and imagine", but achieves a palpable 3-D quality to the sonic that is rather hard to describe.
The "rolloff" you have heard about was not noticable in application and has not been measured, but theorized (by Brian)due to the position of the WG in relation to the tweeter.
He has decided to use a simple and elegant solution to defeat such, if it is the case. That is, he will remove the "horn" that the tweeter is loaded into, to "reduce" its response over 10kHz, to "theoretically" bring it back to spec'd flatness.
But back to how it sounds?
You simply have to hear it. I played every reference cut I had (I arrived each morning at CES 2-3 hours early and played with the equipment and set up)several times and the effect is an great step in audio reproduction.
Wave Guides are not new,in fact a simple horn is a wave guide, but this application to a speaker driver that is generally thought to be extremely "beamy" and frought with "hot spots" is now living up to its potential.
The responsiveness of ribbon and planar drivers, in a now "smoothed" delivery system is a very special sonic, and should not be missed.