I capture most singer/songwriters acoustic tracks live. 

Usually it's not a problem, but when Judith sang - we had a problem: her guitar playing was louder than her singing. 

We could have recorded the guitar and then overdub the vocals, but that would have been a sacrifice, so I thought of using the SE Reflexion Filter to isolate the microphone from the guitar and the results were pleasing - we achieved a nice balance between the voice and the guitar.