I finally got a chance to briefly audition the whole line of CustomArt demos. Unfortunately, I can't really say much about the Pro330, because I think there's a slight problem with the demo unit. They didn't have the Music Two demo, either, so I can't comment on that.
However, I did very much enjoy the sound of both the Music One and the Pro210.
The Music One is quite impressive for a single-driver model; I dare say that, for music listening and enjoyment, the Music One is far more enjoyable than the Pro100 (that I have) because of how much more dynamic and alive it feels. There's a bit of residual bass decay that makes bass feel tactile and layered, while the Pro100's bass is very measured and conservative. Same with the rest of the spectrum; the Music One has more treble presence, but isn't harsh. Transparency feels about the same on both models, though I've only ever heard the fully-custom Pro100, while the Music One is a demo, so the Pro100 may have an advantage. Details feel slightly more "overt" on the Music One, however.
Moving over to the Pro210, it's definitely a different beast from the Music One. From my previous conversations with Peter, I knew I'd like the Pro210 quite a bit, but it really, really impressed me. It's definitely a professional monitor through and through, but a very transparent one, with imaging, spaciousness, and presence that few monitors have. It's open, transparent, and relaxed, but speedy as well, and imaging is very precise. To me, soundstage feels bigger than the Music One's. I don't find the bass lacking, either, though maybe others might. It's tight and speedy, and and keep up with the best of them, without sounding overly etched. There is the slightest hint of midrange warmth that's very pleasant. If I had to make one criticism, it's that the Pro210 sometimes has the tendency to sound a tiny bit nasal, as though the upper midrange were slightly unnatural. At the same time, however, it has a special feeling of transparency that sort of reminds me of the ER4, though the two aren't quite the same. There are still other models that sound more like the ER4, though; the Pro210 isn't designed to emulate the ER4 sound. However, the Pro210 is all about the mids, and all about imaging and transparency. I had my heart set on the Music Two, but the Pro210 is kind of pulling me back... at this point, however, the Music Two will probably still prevail, overall. I'd definitely recommend people get the Pro210 for studio vocal monitoring, however. It seems truly superb for that purpose.
As I mentioned, there might be a slight driver or acoustical path issue with the demo unit of the Pro330 I had, because even with significant fiddling, I couldn't get it to sound all that great. It had good detail articulation, that I could tell, but the highs and lows felt a bit disjointed to me. Again, music wasn't being presented correctly, so I have a feeling there's a issue with the unit.
Overall, unfortunately, the demo units aren't as easy to get along with as acrylic demos, partly because of the thin tubes and the steep insertion angle --- silicone just isn't made for demo use, it seems, but it's nice that Peter has made them for dealers, otherwise I would not have been able to hear these other models.