The better arguments against the DR2d are not sound quality* but its 1/8" inputs, lack of phantom power, limited adjustability and inability to accommodate very hot inputs and no multichannel playback capability. The Dual feature works fine, writing two stereo files. Although you can't see both simultaneously, you can switch between visually metering levels of both input pairs, however you can not switch the headphone/line-out monitoring (given that limitation, it's metering is far superior to that of the DR680 and even that of the R44).
Sound wise, I feel the DR2d with an external preamp (the soundboard in this case?) is comparable to that of an M10, R44 or DR680. I have no hesitation using high quality microphone with the DR2d as long as they get phantom and gain control elsewhere. As long as those caveats are acceptable, IMO the expensive mics / cheap recorder argument doesn't hold water.
An R44 would be my first suggestion as the best all around basic 4-channel recorder but is well out of the price range.
*[edit- I'm sure the DR2d's noisefloor and dynamic range specs are nothing spectacular, but he won't need anything close to even 90dB of dynamic range to record bands using excellent mics in a bar anyway. I'm satisfied using it with external preamps for 4 channel classical recordings with low ambient noise floors and large dynamic swings, which are far more of a challenge for the recorder]