Hi Dave,
Basement gave you a lot of very useful information. I am not an "expert" as some are, but I have owned numerous very nice Nak decks (680, ZX-7, ZX-9 and CR-7A) and I used to be assigned to a Nak e-mailing forum for a few years where there was a lot of information shared, I don't know if it is still up and going.
As for TWL's experience with the Tandberg, I will be clear in that I have never owned one, but followed discussions in like manner before, from those that owned both Tandberg and Nak and those that serviced both. The Tandberg (3014) is a very good deck, BUT it will not "easily outperform any Nakamichi, including the Dragon" as TWL says. Basement already did a great job at covering why one "may" think that if all isn't right.
I would like to further add that Nak decks have a far greater following and as the use of cassette decks dwindle, IMO it will be easier to get the Nak serviced than the Tandberg. I will mention www.eslabs.com as "probably" the most qualified to work on Nak decks. You don't find any 3014's for sale as they are rare.
The nice thing about the two decks you mention is that they have auto-reverse, which can be quite nice; if this is very important to you, don't give it up. I agree that there are better Naks than the 505 for performance, though when tuned up you may be splitting hairs; as for the Dragon I have read that it can be tempormental, but when working great it is a great playback deck.
You mention that you do not want to bother with calibrating the deck when you record, a deck like the CR-7A will do it for you at a touch of a button, but no auto-reverse.
Vvrinc, you are correct, Nakamichi used ZX-9's in their recording studio.
As Basement alluded, all decks need to be properly aligned. I don't care what deck you record a tape on, if you play the tape on a deck that isn't properly aligned, the tape will not sounds its best, no matter how good the deck is. On the same token, if a deck out of alignment records a tape, though it may sound fine being played back on the recording deck, it may not on others.