The folks at the Decware forum are a good bunch, on the whole. Several of them have moved on to or have experience with other amps. Perhaps someone there has heard the Cary and the Zen, side by side. I have not, though I am familiar with the Wright and the Fi 2a3's.
The Select was my first tube amp, and I enjoyed it while I owned it. It's light on it's feet, has great imaging, good detail and strong presence. Even when paired with 4ohm 96 db speakers, I found it to have limited bass extension, and not much weight at all to the bass that was present.
It responds well to tube rolling in all positions, so you can tailor the sound quite a bit. I found it sounded most pleasing with a Bugle Boy at input, Mullard GZ34 rectifier and the stock 6bq5 output tubes.
Upon first installing my Korneff 45 into my system, it took all of twenty seconds of play of the first cd I tried to realize that, to me, the Korneff is laughable superior to the Zen in every conceivable way. The Korneff is better extended, more detailed, and more realistic. It sounds like real music in my system. The Zen never did.
The traits I recognize in the Korneff seem to exist in some degree in all dht designs I've heard, and they are absent in the Zen. Now that I'm more experienced with tube amps, I feel the Zen is a good value and is a good amp for someone that prefers their music to be lightweight and analytical. If you like your music to sound like a live event, the Zen may not be ideal.
This is all my opinion, of course.