I D'Aed in 1987 and began teaching high school in 1992. I've had a number of JWs and it never was an issue, some knew. Most did not. One from about 8 years ago came out to our table at the restaurant where she works to sing happy birthday to someone a few weeks ago. She was borderline when she was in my class (borderline jw that is, decent enough student), but the restaurant scene is now one of my "happy places."
Interesting note, though-if a JW parent requested to have a their kid removed from a DF'ed teacher's class, for any reason relating to the DF or religion, in a public school in the United States, the school administration cannot do it. It would violate the teacher's First Amendment rights. A JW teacher would not be able to have a DFed student removed from her class for the same reason. Doesn't matter if "minors are involved." If a public school administrator did move a student from the class for that reason, he or she could get in a whole lot of really bad trouble if the non-JW found out and decided to take legal action for violation of her civil rights.
La Capra