I have used these three plugins to set up a volunteer registration for signing up for events.
1. Installed all 3 plugins.
2. Set up a form in Gravity Forms.
3. Set up all the Custom Fields in Tribulant's Plugin to match the fields I put in Gravity Forms to get Meta Keys, except for the Event Espresso fields.
4. Set up the User Registration with the Custom Meta Keys that matched all the keys for the Custom Fields as well as the Event Espresso Meta Keys (event_espresso_address, event_espresso_city, event_espresso_state, event_espresso_zip, event_espresso_phone) and mappted them to the form I created in Gravity Forms.
5. This allowed all the content submitted in the form to be added to the User's profile and the event extra fields were also updated allowing for easy Member Event Registration.