Hi Gumby: It's great to see you instigating a post! How are things going on the "inside?"
I can address this from a Christian perspective. My family and I have been involved in a number of different denominations over the years, and yet we were all drawn close together in the brotherhood of our common personal relationship with Christ. And even when we left one denomination and attended a different one, we were never shunned, and maintained certain friendships despite the changes (the other friendships subsided with lack of time given to them, but there would never be any shunning involved and we sometimes attend festive "reunions" where we are all welcomed back with loving arms).
This is based on the understanding that the universal "church" is the "body" of Christ, made up of "believers" from all over the world, in any denomination, as long as they have trusted Christ alone for their salvation. It is not monopolized by any one group--so when I meet Christians when I am visiting another country, we do have an instant bond and unity (as happened recently at a ball-game, of all places).
That has been our experience, and we have not been impressed at all with the hollow, one-sided love proferred by the Witnesses.