@O_Brenner 

I think the easier way might be to setup the OC300 as a new controller, and then with both controllers running, migrate each site from your software controller to the new hardware controller.  There is no backwards path that works for the entire controller yet.

Hi @O_Brenner 

Thanks for posting in our business forum.

Lower version> Higher version = Doable.

Higher > Lower = No.

Due to the new features implemented in the newer one, its config would not pass the verification on the controller's migration or import backup. So, don't do that. That would not work.

  @O_Brenner 

Correct.  Backward 'Controller' migration is not an option, so your only choice is to move each site, one at a time.  I have not personally done a one-site-at-a-time migration yet, but I have moved a single site.  Please expect a few minutes of outage (it has been my experience that when a router is re-adopted, it is also re-provisioned and this seems to cause 3-5min of downtime) and plan your migration time accordingly.