Playing Guitar in a bluegrass band can be tough when you play a fingerstyle guitar. Most mics feedback awfully when you get them turned up to pick up the full spectrum of your guitar. Pickup's are a real challenge to get a accurate sound reproduction out of. I bought the SM 137 to replace an Audix I5 ( like an sm57). The SM 137 picks up sound incredibly well. I find that it sounds best when my soundhole is between 6 and 12 inches from the mic, and the reproduction is really fantastic. It captures the guitars delicate highs, mids and lows very well, even when playing with my fingers.
This piece changed the live music game, when trying to compete with the mandos, banjos and dobros, I don't have to get the mic inside the sound hole to get it to pick up well. This Mic is prone to feedback some when playing in very cramped quarters so you'll want to make sure that you don't have a lot of acoustic bounce in front of where ever it is aimed and turn it up slow.
This is probably the most expensive non- OMNI mic that I have ever used, but I appreciate the sound so much more than the next step down in instrument mics that I felt compelled to review this thing. If you are considering an SM 57 or i5, I would spend the extra money and get an sm137, I was impressed straight away, and I'm very happy with the way this thing sounds.