Vik,
In your cases as an enhancement further, what about having an AUTOFILL feature that randomly picks b/w FILL1 - FILL4 for each ARRANGEENT? I believe this is possible - just needs a random-number-generating loop (1-4) that feeds into the FILL FUNCTION call. With the auto feature ON, even you can't tell what the next fill will be within the arranger.
Cool!
AJ