I've ran a couple of tests myself taping live music in bars. NMJ3 vs DAT vs MD. In short I preferred DAT then MD then NMJ3 but this was before the latest firmware for the NMJ3. The levels on the NMJ3 seem to work now and I don't clip my recordings as easily on the NMJ3. The main difference I seem to remember is better bass sound on the DAT. I've only done a couple of live recordings with the NMJ3 since the updated firmware and I'm pretty happy. The wav file looks normalized when graphed!? Most of it all shaved and linear, hardly any peaks and troughs. strange to me. Anyway, with the fast music transfer to computer via firewire I will be doing more NMJ3 recordings in bars but for big shows I'll bring my DAT or if I have to stealth it then a MD.
Nobody's had any problems bringing in a NMJ3 during a pat down check

(looks like a cd player)