I may be chiming in a little late here, but thought this might be of interest.

A couple of weeks ago I saw a small bluegrass/old timey group at an outdoor Bar-BQ using two Rode NT 2 microphones in much the same way as mentioned above. I'm not sure but I believe they had two smallish Mackie speakers, and NO MONITORS ! To my ear they had the perfect set up for a small "acoustic" group.

The players were a dobroist, who also did some clawhammer, a bass player who ran a pick-up into a separate line on the board, and a mandolinist/guitarist/vocalist.

The dobro came through loud and clear, as did the mando, guitar and vocals. They seemed to work about two feet from the mics, and, being a trio, didn't have to do any complicated choreography.

When I asked about them, the owner said the mics could either be set in an Omni or a Cardioid pattern, and they set them as Cardioid and angled them at 45 degrees away from each other so as to avoid phase interference. He was recording the gig on a mini-disc, and has already recorded one CD of good quality using this set-up.

These Rode mics are normally about $800 US, and are made in Australia. They list for about $400 in the Musicians Friend catalog and online. You might want to check them out.