There is a guy who used to, or maybe still does, demonstrate Korgs who is really good. Can't think of his name.
Barry, on the Keyboard Player group in England, is excellent, as are many more who post there regularly.
There are so many ways to use arrangers, the question can't really be answered, in my opinion.
My "niche" is playing live, emulating guitars and other instruments, and trying to satisfy listeners. That is just the tip of the iceberg when it comes to what can be done with arrangers.