I've been an orchestral musician for more than 25 years, and I've only recently started doing binaural recordings with a MD. I recently purchase a set of Core Sound binaural mics, and I've had occasion to record a Bach oratorio, a symphony concert, and right in the pit at the opera (damn, my cymbal crashes sound loud!).
In a nutshell, they have been the greatest thing since I don't know what! Quiet, unobtrusive, and the sound stage and presence you get in the recording is amazing. They will help a lot in getting a 'real world' perspective on our orchestral sound, rather than everyone focussing on how it sounds on stage.
I've had 2 or 3 cheaper, single-point stereo microphones before, all Sonys, but the noise floor was so high that the recordings were unlistenable. One quick order and some overheated plastic on the credit card and I'm a happy musician...
Cheers,
Jon