Low "self-noise" is very important to me. I do on location recording of classical groups (string quartet, brass quintet, piano and soloist, etc.) and, apart from a wide dynamic range, often times the playing becomes very, very soft. For my situation, low noise is a must. I'm using Rode mics, in part, because of their quality sound, low noise and because they're in my price range. Possibly, in a more controlled studio situation, low noise might not be much of a factor.