Hi Hammer
Not the most popular of Roland keyboards worldwide, but those that have them tend to hang onto them as they are a cracking live sounding board, (Make sure it has or update to OS2 or above to really hear it sing) so it is seldom that they come on the used market. (There almost as rare as a Wersi when it comes to used instruments, with their owners just as tenacious)
Styles from the E series can be used, and there are plenty of 3rd party styles available. (Until Wersi introduced the OAA, (Using its own styles NOT the Yamaha style play capability) the Roland styles were always my favourite out of all the manufactures)
Hope this helps

Bill