I have use the enrollment link for new people, mostly...
It took a few rounds to get most of the bugs worked out.
Items that I configured to make the enrollment work better.
1. Limit the ministries available for enrollment, particularly with our acolytes where certain skills are needed for some sub-ministries
2. Ensure I'm copied on the enrollment, so I can validate the responses
This thread has given me the idea to add a note in the enrollment, "if you get an error that your name already exists, contact the admin"
For me the benefit of self enrollment risk of duplicate users with the above limitations is far better than having to register new users myself, the automatic email with credentials and how to links is very helpful.