I'm using a NT4 for three years both for music and field recording. I'm happy with it and never had any issue; handling noise is more than acceptable and could be further reduced with a Rode pistol grip shock mount; its S/N is good enough for nature and ambient recordings.
I have no direct experience with any AT stereo mic, therefore I can't do any comparison.
If you like to listen to some field recordings you find them on my soundcloud page (
http://soundcloud.com/moooose):
- Night ferry droning, First up then down and Gloria in excelsis Deo were recorded with the NT4>SD 702 (P48);
- Zen gathering, new year's eve and One-stop ride in Milan subway were recorded with the NT4>Sony D 50 (pip).
If you like, I can PM you some concert recording samples, let me know.