I used a Tandberg TCD-310 MkII and a Tandberg TCD440A since the early '80s and still own them. They were full of neat design tricks, sounded as good as anything out there at the time, rewound a cassette faster than anything ever made, and were built like tanks. But to maintain peak performance they were a bit tweaky, and things did get flakey after many years of service -- I can't remember how many hundreds of dollars my Tandberg repairman got over the years. The 440A was designed in the early days of metal tape so didn't take full advantage of that format. I finally gave up keeping them fully functional and rather than having them totally overhauled for even more bucks, bought a new Nak DR10 and a slightly used DR1, their final generation of decks.
This took me well into the '90s and presumably everything Nak had learned about making tape decks. The flutter spec is half of what Tandberg spec'd, and that gave me the biggest sonic improvement, a more focused soundstage -- even with tapes made on the Tandbergs. I can dial in any tape to sound perfect, but I do miss the Tandberg build quality, excellent mic inputs, rewind speed -- good as the Naks perform, they look and feel like any other Japanese mass-market electronics.
I would agree there were some excellent tour-de-force decks by several Japanese mfgs into the late '80s, but as a poster said, they'd by now benefit by going through and replacing some of the cheap caps and components to keep them at their prime. The NAD 6300 was also a great deck combining Dyneq and HX-pro, but let down by a cheap clunky transport. I haven't seriously heard the final generation of Tandbergs (3014, 910) but would bet they're as good as anything out there.
Finally why no mention of the Nak DR1? I suppose I could find out on Naks.com, but despite lacking the auto-biasing and a couple features of the earlier-gen ZX9 and Dragon, it seems they retained the most useful features with newer electronics and transports of the '90s vs '80s to make a deck that should at least equal their previous generation models for a $930 msrp.