Are there any unique wiring configurations to consider when installing the WR2 with a controller? 

The WR2 is compatible with all Rain Bird and competitor controllers.  For those controllers that do not have an onboard power source, a separate 24VAC transformer will be required to operate the WR2 Controller Interface. Proper wiring instructions are found in Section 2 of the WR2 user manual (PDF: 6.7 MB). A unique wiring diagram for the ESP-MC and ESP-LXM (PDF: 229 KB) is also available.