Just finished with two C-179's in fig-8. He was sitting no less -generally that means even less distance between the guitar and voice. The mics were about as close together as they were from the source, still very good isolation on the vocal, decent on the guitar.
..I coulda woulda shoulda maybe used a pop filter on the top mic. 10 songs, about a dozen notches to do in the gain automation.
Why do you love them so much? "Because, they stand on a wall and say nothing is going to harm you tonight, not on my watch.