Oh good post, not sure though, I had heard the song Danyl sang soley due to watching Whitney the hour before on Oprah, and she ended the show singing that same song, she also sang it better than Danyl, and dont all jump up and down, behave I am a huge Danyl fan but I am also brutally honest as well.
I think the audience at home need to know the song, however saying that a song that has been overdone and overcooked can be annoying, and both the ones you mention have been well and truely done to death, the other one I see as being in that category and to be honest boring into the bargain is Twist and Shout that Ollie is doing, I hate the song, but it will get the audience going in the studio which I think is why it has been chosen if the leaked songs are in fact correct.
Joe has a good song, and it has not been done to death and many people not only know it but like it, but he is going to have to do a good job with it or I fear he could find himself in the bottom tomorrow.