AJ,
"The FILLs for the XD-series are on the left side. When using the arranger (unless in BASSIST, PIANIST or MANUAL bass modes) the right hand is usually more busy than the left playing, so most arranger control features are on the left-side. Features that are either used once per performance or rearly used (e.g Intro/Ending) are now to the right as well."

Do you mean that the intro/ending buttons are separated from the fill-variations buttons? That doesn't seem to make sense.
Of course I'm used to using the intro buttons as extra "breaks" on the Yamahas.
Don