Effsee, the point I was trying to make about Runrig etc. was that they don't stick rigidly to a particular "correct" style all the time, especially with their accompaniment!
However, now you mention it, I have a vague recollection of hearing or reading somewhere that Karen Matheson of Capercaillie wasn't a native speaker, but I can't be sure about this.
    Something else I meant to say in case any of you don't already know is that if you go to www.bbc.co.uk you can probably find your way to Radio nan Gaidheal (I had to click on "Alba" last time to find it) from where you can print out the weekly Litir do Luchd Ionnsachaidh (letter to learners) and listen to it being read out (click on Eist a-Rithist).
    One thing I try to bear in mind is that when I went to listen to the Mod the judge complained that nearly every singer was failing to pronounce their broad and slender Ls correctly. This isn't the easiest of things to get right when singing, but I'm doing my best!