For full disclosure I am not a professional and only record myself.
I have however had the good fortune to have been able to record in a few professional recording studios. 10 songs In NYC, 4 songs just outside Nashville, 3 songs in Palo Alto.
I play and sing and have used the one LDC mic (all at once technique) I have used 2 mics (both 2 LDC and 1 LDC, 1 SDC ) all at once technique And the guitar and vocal separately (overdub) technique . All of them work albeit I think all have slightly different strengths
That said IMO I think we as home recordist (if we have the gear) should experiment with all three
Also and getting back to the OP, now if I'm going to record a vocal and acoustic all at once (Which I still do along with also over dub).
The technique in the video Al posted would be the one I would choose
By the way I could not get the embedded video to play so here is the
link
https://www.youtube.com/watch?v=3WrM...ywAXwM&index=4