I've come to this thread very late; but that's 'cos I've been back in full time work in the last few weeks (I'm not used to it!!) and not been checking in here much due to real life intruding...

Anyway, having read through the thread (& very interesting reading it made too), I had a listen to the Charlie Zahm track and I don't really see where the purported "affectation" lies. He seems to be singing pretty much in standard, BBC English, which I'd've thought is pretty much a common lingua franca for anybody born in an English speaking country regardless of nationality, ethnicity etc. Maybe the vibrato isn't to everybody's taste, but that's something that occurs naturally in many singing voices (mine included) and is a matter of phisiogomy, not affectation. I liked it a lot.

Of the singers I hear in a live context regularly, I know many who sing in a different accent to their own, many who seem to adopt a kind of hybrid between their own accent and mid-atlantic, and a fair few who sing pretty much 100% in their own accent. I like some of each, and my judgment tends to be formulated on the basis of what I think of their technical abilities as singers rather than which of the three categories they fall into. Personally, I sing in my own accent 'cos that's what seems to be most effective with my particular set of vocal chords; although admittedly my speaking voice is a lot deeper and more nasal (I'm happy with my singing voice but I do cringe whenever my speaking voice is played back to me...but that's by the by).

What works best tends to be whatever approach the singer feels comfortable with, in my experience...and if they're technically decent, you can be sure that for every listener who turns their nose up, there'll be at least one more who's appreciative.