It all depends how you want to use the arranger.

Pa500 is a great keyboard.I used to have pa800 and loved it.

If we are talking styles,than BK5 is much better than pa500.Especially if you download missing once that are on bk7m and e80/g70.They sound great on bk5.
I only wish bk5 didn't have speakers.They are really bad.You should try both keyboards on your PA system.That's is where bk5 shines.It sounds as good as "the big guys".


But it's up to you.