I tried using the karma on my Kronos like an arranger...
Sadly a battle i lost...
While your scenes follow chords (also possible with the arps on a motif). There is no way the depth and predictabillity of an arranger.. No fills, no intros... Just different patterns...
But also almost no contemporary stuff... Only moden stuff, not suited for the general keyboard artist and its crowd...
And programming your own Karma stuff is incredibly more difficult then making your own styles on an arranger
Aa i said, a battle that i lost...
karma is just different, its awesome for improvising and stuff like that, and just playing around with rythms and patterns.... But not as a substitute for arrangers.