I have an L.R. Baggs Lyric Acoustic Guitar Microphone that’s in the chamber of my Godin Multiac that I have wired to a separate 1/4" jack and volume pot. The guitar I use for MG3 has a humbucker and piezo (in addition to), and currently an unused Hex (which I will eventually use, but right now I don’t have an intermediary device to get it into MG3). I am considering using the Bagg Lyric for MG3 as this allows me on the guitar itself to control each type of signal separately with old fashioned manual controls. Is there any issue with me using this type of Mic? and is there any way to tell whether MG3 is getting the right amount of signal to operate?
Why not testing out and report back to us on your findings? 
Well it definitely works… just wasn’t sure the impact of the quality of the signal. I was just wondering whether MG3 has a way of monitoring input quality…