I think people are confusing quality with versatility when it comes to choosing between audio recording with the camera vs. minidisc and even wireless vs. minidisc.
When deciding what piece of equipment to use for what job you have to put things in perspective and order of importance.
If the room noise is just that, ambient sound or white noise, then the minidisc would be overkill in my opinion. You should make it a habit to record 1 - 2 minutes of ambient sound on your camera in every location you shoot. This can then be used as a looped bed track for background to your main audio.
If the room noise IS your main audio such in the case of a concert band then this is a different scenario. The minidisc itself doesn't record better sound but the location you are able to place it may allow for a better recording. In other words if you are at the back of a packed house with a shotgun mike and the minidisc is centre stage, which do you think will capture the event with more dinamics?
Also if you are going to be moving around or even panning your camera, the audio quality of the camera mic will suffer. It will provide a backup but would not be your first choice. ALWAYS record audio even if you don't plan on using it.
Now you have to decide on the write tools to represent the sound as close to the original as possible. I would suggest using a PZM mic attached to your minidisc in a centrally located area near the band. The placement takes some practice and requires some understanding of dinamics of different instruments. If this is an orchestra, generally all instruments are arranged so that the conductor and the audience will get even sound from all sections. If it's an amplified music band like a rock concert then a feed directly from the sound engineers board it going to be your best bet. In any of these situations a shotgun mic is going to be too directional and limiting. At least use an omnidirectional mic with a wide dinamic range if you can't get a PZM.
The minidisc is a great tool and allows you to hit record and forget about it for a few hours. But if not used properly you will end up with a few hours of completely useless audio at the end of the shoot.
If possible get in for a rehearsal and do a few tests both with the minidisc and camera positions. You'll sleep better and be much more confident the day of the production. Don't leave things to chance.
: I have a VX2000. Would it be better to use a shotgun mic with a minidisc recorder to record room noise as opposed to the mic on my camera? Would the quality be better?
: I also want to video a concert band concert. I'm thinking the minidisc would record better sound? Is this correct?
: Thanks for any info!