Different plectrum materials and different plectrum thicknesses have different sounds. Altering where between the bridge and neck you are picking the strings will affect the sound a lot. New, old, Elixir, phosphor bronze strings, etc, all make significant sonic differences as well. Use and do what suits the song being played. It may take a bit of experimentation to get things right.
Also the inherent sound of your acoustic guitar is important. If it sounds great acoustically i.e. it's a Collings, Santa Cruz, etc, then you'll be able to get a great recorded sound. If it's made out of pine plywood and cost $50 I suspect that hell will freeze over before you make it sound good on a recording. Also the body of your acoustic guitar is important. If you want a dreadnought sound, but only have a parlor guitar it's just not going to happen. Your guitar needs to sound like the sound you want to record.
Personally I have found that
my Taylor 510 using Elixir 12-53 nanoweb strings and Jim Dunlop Tortex .60mm plectrums sounds pretty good for a lot of acoustic players I have recorded.
The MXL V67 should give you a good recorded sound. I'd personally position it about 12" to 15" away from the guitar positioned parallel with the guitar body and pointing at the middle of the fretboard where the neck joins the body. From there I'd move it up to a few inches in any direction and maybe angle it slightly depending upon what it was sounding like.
If you want a mic that responds slightly quicker to the sound of an acoustic guitar you may want to consider using a small diaphragm mic. I use
an Oktava MK012 and it sounds clearer and more detailed than using an AKGC4000B or Rode NT1 (which sounds similar to the MXL V67).
You'll also need to consider the sound of the room in which you are recording. The further away from the sound source your mic is the more of the sound of the room it will pick up. If your room accentuates certain frequencies it can make your acoustic guitar recordings sound pants and you'll find yourself having to compensate for the room sound with mic positioning and eq.
When you are trying to fit acoustic guitar into a mix you'll usually find that the recorded sound has too much bottom end. Use a high pass filter to take off enough bottom to get the guitar to sit nicely. The sparser the mix the more bottom you can leave on. I generally start with a filter at 120Hz and take it from there.
Pete.