Dependability is not an issue. Unless I don't understand the question? I change the tubes myself, simply open it up and swap them out. The low output voltage doesn't make a difference in my system, but then again, I have a pre-amp. Perhaps the low output voltage would be a concern to those who use passive volume controls.
In summary, I have no regrets at all, the Zanden makes my CDs sound better than I have ever heard before. Last xmas I was looking at vinyl rigs and heard some very $$$ setups (those outrages setups > $50k). Do they sound good, of course, but now, I really don't have a desire to get into vinyl because I don't have a vinyl collection to begin with. I did the silly thing of trading all my vinly in for CDs back in the early 80s. Bad mistake. I seem to learn the hard way...:)
Regardless, if you're interested in the Zanden, then do your best to try to hear one, its well worth the effort. Unless you want to take a risk and buy one sight unseen - which is what I did. :)
My short list came down to 2 dacs: Zanden and EMM DCC2. My reasoning was that I love tubes and there was a used Zanden listed on here, so I grabbed it. Maybe I've transitioned over to a hard core tube lover. :O
Good luck with your journey!