That is all good advice… For me, I recently recorded some samples at different mic positions, I would recommend that you do the same and hear the difference for yourself. The results of my test pretty much agree with what everyone says but sometimes it helps to hear it for yourself. I’m sure how the guitar sits in the mix is also a big factor in where you place the mic, and then that would also depend on what kind of music and guitar tone you’re recording. If you want, you can check out my recording samples at http://www.soundclick.com/bands/default.cfm?bandID=1007794&content=music and check out the “Mic Test” clips. FWIW, I recently asked a recording engineer for his advice and he too said that he would normally use two mics, one right on the speaker grill and another placed 2 to 6 feet away and mix between the two, and he never placed a mic dead center on the speaker.