When a 'big star' does something like this at a concert the audience generally eats it up - I saw Paul Anka do something similar to "My Way" with a Frank Sinatra video and the audience loved it - BUT - that is much different than a OMB doing it ... perhaps used as Scott says - intermittently, maybe even in place of a vocal harmonizer - it MIGHT work, but IMHO, not as a full time gig ...