Jafox:
Just like Marlan Brando in "The Godfather," I grant you this information now, but one day I might call on you for a favor. Don't worry; it'll be small--a pint of Guiness if I ever make it to the Minneapolis area. :)
The original intent was to pair the Tenor 300s with my Kharma Midi-Exquisites. That pairing didn't turn out very well; I got swayed by all the hype and bought the Kharmas sight unseen. Big mistake. The Kharmas were absolutely lifeless and undynamic. The 300W of the Tenors did something to jumpstart them, but not nearly what I expected. At the time, I thought the problem was the amp--and the Tenors had been acting up (blown tubes, bad balanced output, etc.)--so I got a pair of DartZeels in for audition. When I hooked them up to the Midis, the result was much the same as with the Tenors: some dynamics, but largely lifeless.
It was then that I suspected that the problem was not the amp, but the speaker. To confirm this, I pulled out my Von Schweikert VR-4 HSEs, which were doing duty in a two-channel home theatre system. BAM! With either amp, the speaker literally exploded to life. I saw the Kharma sweating in the corner; it knew its days were numbered. Now that I had a suitable speaker to judge the amps with, I was on my way. Over several days of comparing, I came to a few general conclusions: (a) The DarTZeel was every bit the match dynamically for the Tenors, despite a 200W disadvantage. And I thougt those dynamics flowed effortlessly. (b) The DarTZeel had a smoother, more natural presentation, without glossing over any low-level detail. (c) Speaking of detail, the DarTZeel clearly revealed more information, doing it absolutely effortlessly. The transparency of this thing is amazing. (d) Reliability. Here's where the DarT pulls away. The NHB-108 is handbuilt to ridiculously high standards. (That said, one amp had a loose fuse rolling around inside--a refugee from the construction process--but seeing that it wasn't doing any harm, I left it in rather than ship the whole amp back to Switzerland.)
The Tenor isn't shabbily constructed either--it's actually rather beautiful--but the DarTZeel is built like it could withstand a direct hit from a Scud missle. To say that it's built like a fine Swiss watch would be an understatement. The attention to detail throughout is staggering.
I hope this answers most, if not all, of your questions. BTW, those JL-3s of yours are sweet amps. I heard them in New York a couple of years ago. Definitely worth a little fiduciary recklessness!