Michael,
Yes, I did use Register Plus Redux, the custom fields did appear in the profiles, and changing values in the fields and Updating them worked. It’s puzzling that you are not seeing the data in the new fields.
I found that I made heavy use of phpAdmin to view (and experiment with) the tables wp_users and wp_usermeta in my WordPress database, where all the custom data is stored. Have you looked at these tables? Is the custom data there?