I've been going through the new rigs one by one in Rig Manager and previewing them on the Profiler, keeping the ones I like and skipping those that already exist.
But are the older / existing rigs updated? Should I just import them all?
Note: I've avoided doing this because I've had bad duplication issues in the past, where I updated the 5.1 or 5.5 content (I forget which) and all of the sudden I had dups of butt-loads of rigs. That took a LONG TIME to clean up. However, I just did a test, uploading the first 3 rigs in the 5.7 content, only one of them with a new name, and there are no dups.