Boring aspects of Arranger Keyboards for me are:

1. Unmusical bass lines especially in jazz walking bass and salsa. Not sure if an arranger keyboard will ever be able to anticipate what chord is coming up next, so the results are simply unmusical and not stylistically authentic.

2. Chord recognition is very limited on all the keyboards I've tried which limits me greatly.

3. Breaks and unison "tuti" rhythmic are hard to pull off effectively.