No offence Lee but to me this is astonishing, probably because I am a home musician and never gig. Yamaha have gone a long way with their songstyles ( too far imho) but what on earth could be the point of reproducing a song as close to the original arrangment in your ARRANGER keyboard ? As several have pointed out the beauty of the arranger keyboard is that you can arrange. I cannot imagine anyone being interested in my renditon of My Way or Like a Vergin for all I care, if I record and sing it reproducing the exact song on the keyboard....
Midifiles can do that trick, better still Karaoke files can do that trick and best of all good original Backing Tracks can do that to a T.
In your approach, at least that is how I see it, you would be better of with a good wireless mike, a great amplifier/speakers and a tablet or laptop. But I may have a rather unique view of the matter, forgive me .....

regards,
John