I used to be, and rarely talked about it among my colleagues. Once the ice was broken, however, I have never been treated badly by workmates for having been a JW. In fact, I'm sought out as a resource whenever we get a patient whose chart indicates that they are JW. I've even arranged for community support for patients who have been DFd and have no support network or family support due to being shunned. My personal goals this year included working with JW patients (I had an arrangement with my colleagues previously where I didn't work with JW patients - I was worried that I might lose my objectivity and say something that would cause problems for me professionally or personally).
Over all, I would say that the results have been very positive. My friends know that I was "raised in" the JWs, and due to the tight information control, had no frame of reference other than what the WTS provided. They don't hold it against me, and they know that once I saw through the bullcrap, there was no turning back. They've been very supportive, and some have even made a point of including me in holiday stuff because they know the situation about my JW relatives shunning us. I couldn't have asked for better friends.