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The variations on any BiaB song go far beyond the substyles on any arranger keyboard. There is "A and B" in which B is often a little more energetic or busy than the A. But BiaB goes far beynd that: You can have the C and the D be completely separate styles.

Your A and B might be variations on a bossa, but then C could be a guajira and D a Mambo.

This is only one of the many ways in which it would be misleading to carry out a comparison between what an arranger keyboard does and what BiaB does.

I use both, and for completely separate purposes.

Flatfoot sez: Call me when 'Talent-in-a-Box' is ready to ship! -- [8{>

Got some tunes on You Tube:
http://www.youtube.com/user/flatfoot50
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My BiaB lesson site:
http://jdwolfe0.wixsite.com/learnbiab