When I was a teenager I played the guitar in a band made of friends; gettin golder I lost all my contacts in the music world due to my job and so turned to the keyboards. To have a backing of some kind for my tunes I used to spend a lot of time simply recording rhytm tracks and saving them as midifiles on my Akai MPC 60. When I bought my first arranger (Roland E20) I realized what a waste of time that had been. So I can say that arranger keyboards really helped me to concentrate on music and to free my (however limited) creativity.