I didn't have any trouble understanding your accent but I am Scots born myself. I truly believe that many Scottish accents are clearer and more phonetic than most English accents - the pronunciation tends to be closer to the spelling, with fewer dropped letters and slurred sounds. I can't think that many non-Scots speakers of English would have much of a problem with your accent, and in live performance it would be even less of an issue.

What causes bigger problems for a wider English-speaking audience is broad Scots dialect involving the use of words and expressions that are unfamiliar to the listeners (e.g. some of Burns' songs). But even they can be smoothed out by a brief explanation of key words before the song begins (or by a glossary in a CD's liner notes).

And I enjoyed your lovely singing, too - there's a genuineness and clarity coming across, which I just don't think would be there if you were using a phony mid-Atlantic accent. Don't change!