I have one of these, too (actually, I've owned three and a handful of portable MD recorders). I use the remaining 564 (mostly) as a four-channel mixer (with no phantom power). The pres and strips are surprisingly "clean" and I've always said that if you can't record a drum set with four mics then you need to hang up your "engineer's hat".
The problem (as I understand it) with every MD recording apparatus is that the mechanism which aligns the laser (or the material that holds the "heads" in place) becomes fatigued with use (or storage) and eventually breaks. There's no source (as of the last time I checked; a few years ago in the USA) for internal replacement parts to fix the MD drive. If you can find a replacement MD drive (and that's a mighty big "IF") it's likely to cost a few hundred dollars for the part alone. Frankly, it would have cost me more to fix my 564 than it would cost to buy a "new" (used) one. Which is why I've had three of them. And even if I got it fixed, there would still be a waiting game; how long will it manage to function before the TOC Error comes back? What really burns my butt is that I have dozens of MDs sitting around and I'm not entirely sure what's on most of them. All I know is that I was sick to death of having MiniDisc recorders break on me...
So I spent the money I was planning to use to fix the 564 (plus a bit more) on a truly excellent two-track 16-bit solid-state digital audio recorder. This was before most of the portable decks went to 24-bit but, if I had the money to spend now, I'd still buy the same recorder I bought back then. At the time, I was doing more location recording than anything else (and my back insisted that anything larger than a suitcase was out). The portable deck has served well in-house as well; I recorded the score for a feature-length movie using the two-track and a room mic (and I'm told it sounds "awesome" and when I tell people how it was recorded they usually say that it's "unbelievable"). Platitudes. Bleah.
A last thought: I figure that, if I'm going to record in digital, I may as well use CD/DVD quality PCM instead of ATRAC (which is basically the same thing as recording in MP3). To be perfectly honest, I can't say that I miss MD. I figure that, as long as I don't do anything stupid, that solid-state rig will still be working long after I'm buried (no moving parts = nothing to break). Some of the MD gear I've had didn't even last a month...
