Hello Alexander,
I agree with the comments, but I have to say that the roaming in Ruckus works really fine even without the controller, of course that you have to made a good deployment for this.
The only thing that I don't like about the "autonomous WLAN" is that in case that you have a WLAN authenticated using 802.1X, it doesn't support this type of authentication so you need the controller for this case.
Regards,