If you really want to record, this is the answer. Mac will never add recording to the iPod, and Sony will never add digital upload to the consumer MiniDisc. They're both more concerned about music piracy than they are about providing features to people who legitimately need them.
Unless you want to transfer your recording in real time from the MiniDisc through an analog cable, or pay $4000 for a professional MiniDisc deck with digital out, you're out of luck.
I don't know if you can upload voice recordings from the iPod, but the Apple Store person I asked conceded that the quality was poor.
I'm a singer, and use the iRiver for my rehearsals and performances. It's simply amazing. I plug in a $99 Sony mic to the line in port. I've never tried the supplied mic 'cause I already had the Sony mic for my now abandoned MiniDisc. You may find that the iRiver mic is good enough, though.
There are some inconveniences to using it as a player with Mac. So far I haven't found a playlist generator for OSX that uses the iRiver's M3U format. So you're stuck with shuffle play, or listening to the entire album (or directory) in the order the songs appear.
Also, dragging files to the iRiver drive copies the OSX resource fork with it. So each directory gets a bunch of useless unreadable files which don't really take up space, but the player tries to play them (maybe .5 sec each) before beginning the music.
It's possible to use the terminal to transfer files without the resource forks macosxhints.com has a post on this somewhere, but I keep hoping a third party like Panic will release an app that does it.
The iRiver does display the ID3 tag information- artist, title etc. You just can't search on it or create playlists from it.
I think the inconveniences are well worth it for the flexibility, power and features you get. A co-worker of mine had an iPod, and it acted like a total music Nazi. Songs he transferred to the iPod from his home computer in iTunes couldn't be uploaded to his office computer so he could listen from there instead of exhausting the iPod battery.
And bottom line, the recording quality is excellent. It will encode mp3 on the fly or you can record in WAV if you really need maximum quality. Then just drag it off the player and on to your Mac and you're ready to edit and burn. There is no more powerful or affordable portable recording device for all-digital recording and transfer to your computer.