This said, I have sold three arrangers to guitar playing friends who wanted to try a keyboard.

The way I approached it was that I taught them to use their left hands to play chords on their arrangers. Their right hands could do leads, chords, fills etc.

This made sense to my guitar playing friends as they used their left hands for chords on guitar. They just had to learn to form chords in a different manner on the arranger than they did on guitar.