I was never DF/DA, but they did give a talk about "marking" my brother and I. Which was like saying we're not going to officially tell you not to associate with them, but if you want to personally shun somebody, go right ahead.
And many of the youth in the congregation did so. And some parents. Others didn't.
It wasn't quite as bad as DF/DA. If I said hi to them, they might say or nod a hi back, but then leave. Or some very quick politenesses.
Didn't really bother me much. I had always cultivated friendships outside of the JWs. I saw my friends at school 5 days a week and sometimes other times. My JW friends were mostly just acquaintances. Which I hardly did things with and only even had a chance to talk with before/after meetings.
So in essence, this milder version of shunning didn't really affect me. Life was out there. Other things to do and concern myself with. You want to mark me, go ahead. I'm having much more fun with the things you're marking me over than your touch-and-go, walk-on-eggshells friendship. So, bye-bye.
So the result pretty much is that it drove me closer to my worldly friends. Which helped a lot when I decided to quit in that I had a support network of friends to turn to. And I'm sure that doing things with worldly people also helped me think of the JWs as the "other" which helped me decide to leave too. Mostly Ray Franz's book caused me to stop cold-turkey, but there was also a growing mental divide that got wider with the marking.
As for other DF/DA people and how I treated them, I had no problem. One cleaned the building where I worked. I always said hi to him. Which he later said he really appreciated. Once in a while we talked. But it was just the nod hello or word hello. Same with other DF'ed people I saw.