It depends on the congregation I think. However in the congregations I have known retention is poor. In my own family of 4 girls 3 of us are out only one is in. One of my sisters never got baptised and 2 of us woke up and left.
It is a religion that offers nothing for the young. It is telling that the congregation mentioned by the OP is active in the ministry since this is the only way to gain any approval in the organisation.