We have found that when you have a large number of automatic groups, it can be quite challenging to manage them, especially when troubleshooting issues. We also manage these on behalf of many power users since they cannot do this themselves therefore it is critical that we know what attributes are being used by each group. Rather than managing an external spreadsheet, we use the Group Description field to log the rules...it looks something like this:

Org Level 1 = MO - Middle Office + Company Code = ACME

This has proved invaluable to us.