From long experience, I recommend that interviews and other documentary/actuality material be recorded in X/Y stereo wherever possible. For the average listener, stereo makes the recording much more pleasant and interesting to listen to. And if anyone ever has to transcribe the results, I can tell you--as someone who has spent hundreds of hours doing this, in two languages--that having a stereo recording makes that task far more efficient and reliable. It enables your brain to overcome deficiencies in the setting such as noise (up to a point, anyway) or excessive reverberance (up to a point, anyway).
If you use a one-point stereo microphone, a mono signal can always be derived by summing the two channels; no frequency-selective losses due to comb filtering will occur for sound that arrives directly at the microphone.
--best regards