AB, XY, Blumlein, Mid-side are all techniques which can be used and from which a choice can be made.
But: the technique to be used depends on a) the size of the room b) the size and location of the organ in the room c) acoustics (how large are the acoustics and how does it relate to the room and to the perfect listening-position of the organ) d) what is the best listening position of the organ, etc.
I think it is too short-sighted to reject AB in advance for a recording of each organ in any church. It is a fact that a recording of real acoustics is much more realistic than IR or other simulation methods. However, it requires more skills and insight. During recording, but certainly also when processing/ denoising, mixing and cutting the samples. Yes, multiple releases are necessary (incidentally always when recording spaces with >3 seconds of acoustics) and phase differences can occur, but this is surmountable. However, very good microphones, preamps and A/D converters will help to get the job done well. But in large spaces you absolutely will need omni microphones to record the rear, because with only cardoid microphones the proximity effect can occur. And the proximity effect can't be removed from the recording with any software !
I myself always record in large spaces in 4-6 tracks (very close with cardoid microphones, further away with omni and perhaps even further away also with omni). The distances between the different microphone positions can be calculated and/or you must rely on hearing. What is the best place to put them (the so-called sweet spot)? Afterwards I dub the four rear channels back to one stereotrack. The recording in the front is in my opinion the most important and the rear recording only adds something to the front. Also the final sound-level difference between the final front and rear samples in Hauptwerk are important. Which stops should sound more diffuse as others ? These are important questions to answer (and think about!) to achieve the best possible result.
But again, these are all opinions and experiences. No room or organ is the same and it depends entirely on these factors. An organ in a relatively small church (such as Onderhorst) therefore requires a very different approach than recording in a large basilica with 6 seconds reverberation. And in that case: yes, XY and mid-side might be the best techniques @ Onderhorst, but not for everywhere.
In this video (
https://youtu.be/4WF8TvXAqvw) you can hear the spatial difference between chosen cardoid and omni microphones . And here (
http://www.homerecording.be/forum/attachments/f47/5394d1272655290-fragment-2_c42mp-r88.mp3) is a recording made in Ieper (Belgium) on a large stand with also a large brigde (and omni-mics in AB setting). A mid-side technique would not have been desirable in this large church.
Kind regards, Danny