I just created a policy that worked in IDM 3.6.1 using $GCV-NAME, but when I imported the driver on an IDM 3.5.1 box it didn't work. I used trace to output the XPATH evaluation, but instead of the String itself, there was a reference to a Java object. Strangely, this didn't cause any errors in the driver, it just caused comparisons which had formerly worked to stop working. I had to replace all the $GCV-NAME references with '~GCV-NAME~' to get the original functionality.
I took a lot from your XPATH tutorials, in particular the Association stuff. Thanks for taking the time.