Hi Viond,
I've created the same using survey templates,
1. Created a survey template
2. Created a notification rule and associated the survey template in Notification message template
3. Attached the notification rule to Closed activity.
For every closed activity , the notification is getting delivered to affected end user.
please find the below screens, I assume the same is with Managed Survey's ,pls suggest if something is missing here.
Venkat