Utilizing spaced omnis can result in an extremely open and lush sound field, the downside is possible phase anomalies present when the signal is summed to mono. Spaced techniques also require critical mic placement for accurate results. Near coincident technique works extremely well with larger sound fields such as those found in classical music recording. Along with good localization, listeners will also perceive a depth to the recording space. The technique does not work well when the mics are placed near the sound source as small movements are exaggerated in the recorded sound field.
Coincident techniques provide good sound field location, and work well with smaller ensembles.
XY pairs can be employed very near the sound source and still provide spatial cues. Mid Side technique employs two microphones aimed directly at the sound source. The Mid mic can be of any polarity, but is most often of a cardioid or hyper cardioid design. The Side mic is a bi-directional or figure eight pattern. All the science in the universe isn't any consolation when you forgot to bring the tape.