A few thoughts, none of which are inconsistent with the consensus expressed above (which, unless you missed it, is "Don't get at DAT!"):
- DAT was a de facto standard for exchanging digital stereo recordings at one time. It's not any more. If there's anyone even remotely connected with music or recording who can't play a CDR, please expose him to ridicule. (And even when DAT was a sort of standard, it wasn't really the standard for high-end professional studios -> mastering).
- DATs use a 48k sample rate and a 16-bit word. The difference between this and the 44.1k / 16-bit CD format is not material to quality. About all it means is a DAT can have its anti-aliasing filter at 24k instead of 22.05k. If you think you might be impressed by that difference, don't be: it's about 1.5 semitones.
- There are newer formats available, which use higher sample and bit-rates than either DAT or CDR. The Alesis Masterlink seems to be fairly common, for example.
- Any box that takes an analog signal and stores it digitally has an AD converter in it, which does affect the "quality" of the recording. But there's nothing about the converter in a DAT machine that's particularly different from the converter in a CD recorder (other than the minor sample rate difference mentioned above). If anything, because DATs have fallen into disfavor in recent years, when you buy a DAT you're more likely to buy an older design. If you ignore the converters, all you're talking about is a storage medium.
- As a storage medium, anecdotal evidence suggests that DATs have more problems than CDRs. Also, the tapes are considerably more expensive.
- On the other hand, there are some nice, small portable DAT machines, and you can find them at fairly reasonable prices used. The only portable CDRs I've seen are the Marantz ones, and you're unlikely to find many used ones. This is only relevant if you're interested in highly portable recording and don't want to use a minidisk or something.
- DATs are still a fairly standard format for live-tape exchanges among Deadheads and their ilk (so far as I can tell, anyway). This is only relevant if you're a Deadhead or something similar.