Well, this would depend upon the relationship of course, obviously people in an open marriage don't feel the same way as people in a traditional relationship.
All I can say is that as an ex-JW and a person that values his mental freedom, I'm not much for any activity that hijacks my mind or emotions. Now this doesn't mean being a control freak, but rather I'm not excited about being controlled by any impulse, either. They come, and they go. I don't try to hang on to either state.
For me the problem with cybersex, porn and such is that it's a single element divorced from the rest of the experience. Heck, even if you just plain want sex it only gives you the visuals and maybe some audio right? Of course with sex itself we can say it is often split off from the person, or worse yet there ain't much of a person there to begin with. I just can't get excited over a sexy person without much of a personality anymore, or rather if it's a personality that I'm not interested in I'm really not interested in the rest of it. To me getting into a relationship like that is like going to work at a place that's really boring but they have really good coffee, or something..