I'm slightly puzzled by one aspect of your last post, Grab. I don't quite see that people sing "naturally" when in front of a mic, yet are forced to adopt artificial accents when singing unamplified. In my experience, most singers either sing in a contrived accent or they don't, irrespective of whether there's a mic in front of them.

I sing frequently, both amplified and non-amplified, and I'm not aware that my accent is significantly different when unamplified - I probably sing a bit louder! I certainly have no need or desire to adopt either a "plummy" or a "nasal" accent in order to adequately express myself acoustically. Surely, feeding voice production through a PA is artificial modification in itself!