One of the things that everyone touts on the S900 is the ease of recording the arranger to audio. It's a great feature (wouldn't mind it on the G70), but it seems to me an awful lot of folk want to use it as a 'substitute' for the arranger's sequencer.
Now, unless you ARE just trying for a simple capture to go 'Hey Mom, here's me playing my arranger!' or whatever
I would STILL think it better to use the MIDI sequencer to capture your 'performance', and then you still have the ability to edit out any glaring bum notes, or inadvertent 'glitches' in the arranger engine, and remix for a more balanced sound (we so often tend to lay the tracks down with our RH voices a bit too loud).
THEN, after it is tweaked, you can record to audio. But audio as a primary means of capture seems to miss the whole point of the wonderful MIDI capture capability of most arrangers...
JMO, yada yada yada...