Some of my guitars sound good with mic X, some with mic Y... some work for M/S... some don't... some work here, don't work there. There seems to be endless permutations. My boomier guitars like the crisper mic, the crisper guitars sometimes like a less toppy mic (like a ribbon). Sometimes it's nice to put more mellow LDC up the neck where the sound is 'thinner' and combine it with an SDC pointing at the bridge or lower bottom where the sound is 'thicker'. One of the best results I've had with a Martin CEO-7 was an SDC pointing towards the 12th fret and a Royer 121 coming over my shoulder. Another thing I like doing is recording an LDC in omni, to pick up some room, and then introduce some tight sound from a close up KM184 (or even a DI). Sometimes even introducing a tiny bit of 'hair' on that second track to give a fuller sound. Again, a lot of is down to the 'feel' you're trying to produce. Listen to a band like Wilco and you'll realize that there is no such thing as an 'acoustic guitar sound'. Different song, different guitar, different treatment.
Been reading a lot of production books of late (notably Vols 1 and 2 of Behind the Glass, Glyn Johns' book and Phill Browns') and there are a quite a few engineers who NEVER use more than one mic on an acoustic guitar... or on electric... Some argue that an acoustic guitar is a pointless instrument to try and record in stereo because the instrument itself doesn't have enough separation. If the guitar needs to sit in a mix with other instruments then it might work better with a completely different sound to that which you might consider for a solo guitar performance...
There are a million ways and none of them are 'wrong' if they sound good to you and they serve the music you're trying to convey... (and as long as they don't 'break' if summed to mono or shred someone's speakers
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