As of TrueNAS 11.2-U6, changes to iSCSI extents no longer require a service restart; however, some changes to the device type and path are not updated. For instance, changing from one file to another or from a device to a file works. Switching from a file to a device does not work, though the UI will edit the path to prepend '/dev/'. This change is not reflected in /etc/ctl.conf. Switching from one device to another does not work at all. Nothing changes in the UI or the conf. This behavior is present in the old UI.
In the new UI, on FreeNAS 11.3-BETA1, the path field is not present. An error still exists switching between files or from a device to a file. Switching between devices or from a file to a device works perfectly fine, with no abnormalities present in the conf file or the UI.