Donny - I see your point
Last weekend I was hired as a DJ. I love the 800 Songbook. It worked so well with hundreds of mp3s on a stick. I was able to switch flawlessly back and forth to live play to mix things up. The opening Elvis act wanted Karaoke, so I had 3 songs for him too.
In a nutshell, you do what you have to. Overall, the audience (in these venues) is not that sharp to discern what the heck is going on behind the keys. Many came up to me with compliments about my performance (and this was only after mp3 play - go figure!)
With that said, I will always do live arranger first (I believe the boards are made to get the best sound this way) and all other modes last.