I use my arranger on a OMB gig. I use 80% user styles created and tweaked for my personal style and playing ability and to distinct myself from all the other standard OMBs. That is why changing arrangers every 6 months is not an option for me because I have built up lots of user styles and sequencers that would take a lot of work to transfer to another brand arranger.

In the style part, I usually have 2 drum tracks, a bass and a chord sound. In the left hand, I have piano, organ, strings or what ever assigned for me to play live. In the right, I would have a lead sound for me to play live. Sometimes I would have just drums and bass in the style parts and a full piano in the right (good for ballads).

I use 10% MIDIs or as I call them (Linear sequences). Again tweak to my personal touch.
And then the remaining 10% I use good old drum tracks left hand bass and piano or what ever in the right hand.

Now here is why I really like a full featured arranger. I also use my arranger in a band setting. Its much easier to get to sounds and the ability to tweak sounds and load new samples and sounds gives me a lot of flexibility. And when the band is taking a brake, I
Could play a CD or MP3 during that time.

And of course, as with any instrument, I use my arranger in my studio.