I would go for: set it to global and after initial assignment set it to "freeze" and have this updated manually
Step 3 Choose one of the following options from the Channel Assignment Method drop-down list to specify the controller's DCA mode:
•Automatic—Causes the controller to periodically evaluate and, if necessary, update the channel assignment for all joined mesh access points. This is the default value.
•Freeze—Causes the controller to evaluate and update the channel assignment for all joined mesh access points, if necessary, but only when you click Invoke Channel Update Once.
Note The controller does not evaluate and update the channel assignment immediately after you click Invoke Channel Update Once. It waits for the next interval to elapse.
•OFF—Turns off DCA and sets all mesh access point radios to the first channel of the band, which is the default value. If you choose this option, you must manually assign channels on all radios.
from the same guide (RRM is supported)
In addition, the radio resource management (RRM) feature enables cell breathing and automatic channel change, which can effectively decrease the collision domains in a mesh network.
