Search around for more info, but the reason tapers are using the Nomad JB3 compared to other mp3 jukeboxes is that it reliably records in wav--either 44.1k or 48k wav. It also takes a digital input. So the recording made by my JB3 fed a digital signal by my Lunatec V3 is EXACTLY the same as the recording made by my M1 DAT fed the same signal from my V3.
For open taping when using a digital input, there is much to be said about the Nomad JB3 and more or less it is in the same realm as DAT. Soundwise anyway, other folks have their own thoughts on reliability, durability, ease of use etc. Both the Nomad and DAT are in a different (higher) class than MD.
For stealth taping if you're only using the recording device itself and not outboard mic preamp and A/D converter, it is a different story. I'll let others chime in as I don't have experience running the JB3 with an analog signal. The Nomad will still record 44.1k/48k wav files and is not limited to mp3 recording, but the line-in and A/D converter stages are not the greatest, and DAT is probably far superior.
-Todd