I try to sing in my own voice. I disliked hearing ren faire folks trying to sing in fake English accents. I recall being at an open mic in Chicago where a young man from Glasgow was visiting and he was trying to sing Woody Guthrie in a fake Oklahma accent. I agree with Jim Carroll that most songs can be sung without trying to be dilectic. There are some Scottish songs I love that I wouldn't try and sing because some of the lines would be lost without the accent. But there's not that many.