SM58 in front of acoustic...

i agree. i did that recently and found it sounded damn good. My engineer at the time said she was putting up an sm81 so i said ok, then i walked in the room and a 58 was setup. I said fuck it and listend to it. It sounded pretty good.
 
in the context of what?

in the context of making music with said acoustic... ?

More details please! Position, direction, eq, maybe pics or clips. I think the 57 sounds like shit on acoustics everytime I try it. Didn´t even bothered to try the 58.

uhm, pointed directly at the fretboard between the sound hole and where the neck meets the body...

I won't have a clip for a few days... PM me if you still want them in a couple days... it helps that my bedroom actually sound great for this application and adds a lot of ambiance to the track... oh, and its a $2k Martin... =)
 
here is a short clip of the guitars in wav format... (like 4.2mb)

http://www.blugargoyl.com/temp/srndr_clip_gtr.wav

also should note that the string are like 6 months old... HP at 80... small amount of comp... thats it.

It's a decent tone, works for that guitar anyway.

I've never been a fan of double tracked acoustics, yes it's wide, but the ping-ponging drives me nuts.

I tend to do ORTF 3 feet in front or A-B over the shoulders, head level.