My husband's great aunt was a JW. She was a highly intelligent woman and refused to let her church dictate her love of her family. We saw her for various family and holiday celebrations (she even brought gifts). No one was expected to adapt around her church, not even her children who left the JW's. She was never disfellowshipped over it and neither did she keep it a secret.
On the other hand, one of my best friends, disfellowshipped, has had quite the opposite experience (which I will not go into in this thread....let's just say that it falls under many of the things that have been already mentioned by others and more).
I think I would draw the line at (a wedding in) a local, get teenagers to runaway across state lines, cult group that we have family members in. That would be my line. I have kids to protect.