I'll chime in, as I threw the GTG and played through these, and my wife was the one who played her violin through them.
From a BG perspective, I played my Bongo 6 HS, roundwound strings on it, using two of Charlie's amps. These cabs are studs, and there's really nothing at all that I can find as a negative for them. Even with half of the ports plugged, the TC118 was just ridiculous. The overall response of it was insane, and it "takes" EQ changes nicely. Of course, part of that is the amazing work of Charlie's amps as well, but if the cab can't reproduce what it is being fed, then the best pre in the world won't help you. Even just slight fiddles of the knobs came true. I didn't get to move around a whole lot, but the little that I did had me convinced that the tone across the board is fairly even regardless of your position relative to the cab.
The TC118 is also crazy light. I can pick it up and move it around with one hand. I think Duke said it weighs in at 43 lbs. The form factor isn't much bigger than my 2x 2x10 setup that I sometimes use. Portability with that is astounding - the 115 and 112 have to be even better for sure. Heck, the 112 looked like a toy sitting on top of the 118

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My wife brought along her NS Design CR violin as well. She's a classically trained violinist, who studied at Julliard when she was 11 (by invitation). It goes without saying that she's no slouch or a hack by any means, and was a great test for this. While not a typical instrument that would be put through these by any means, it was a great test of the high frequency extension. The open high E (highest string on a violin) has a fundamental of 659-ish Hz. The highest note (fundamental) on that string is somewhere around 4.4Khz, IIRC. Just to give you an idea of what we were doing, and how far outside the norm for us low end dwellers this is.
We tried several cabs of Duke's designs. My wife and I were both completely, entirely blown away by what those cabs were doing. I never thought I'd see/hear a cab with a primary driver 18" diameter, long excursion do violin any justice. However, the TC118 was super, super impressive. Very rich, full bodied tone. Nothing harsh even on the highest notes. And, much to my surprise, you'd see the woofer moving as well, so it wasn't all just going through the compression driver! All of the other cabs were equally as impressive as well. Some of the cool design aspects made it more interesting, especially for small stage areas - which, I felt bad as I had the vendors here pretty much crammed in along with everyone else, so not a whole lot of room for things to "fill out", as it were.
With all of that said, I don't mean to down talk Greenboy/fEarful designs or anything, but Duke's cabs were much more pleasing to my ears than fEarful offerings for both bass guitar and electric violin. Both are leagues beyond my 2x10 Ampeg cabs I've been using, and it was a great ear opener. I've been on the fence about getting a fEarful for a few months now, but they are no longer on my radar. I will be getting an Audio Kinesis - I just have to decide which one and talk to Duke.
If anyone has any other questions, I can't promise to watch this thread too closely (at least not until I get my own), so feel free to PM me directly.
Edit:
Here's a couple of photos, thank you to Marial. I think the first one is the Hathor 1203, and the 2nd is the TC118:
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I think/hope there's more pics floating around, but I can't find any at the moment.