How good is LinkedIn privacy?

I'm currently a gainfully employed software engineer at a company where I am well-liked and in no danger of losing my job. However, due to various factors, I feel like I want a change of pace. I have a LinkedIn profile, and I would like to let recruiters know to contact me, but if my current job gets wind that I'm thinking of leaving, it might cause me problems at my current job and I might find myself out the door faster than I was otherwise prepared for.

Question: Has anyone set their LinkedIn settings to "actively looking" while still at a current job, and have you ever had problems with your current employer finding out you are looking?

I'm not asking about how to deal with such a scenario, because if it gets to that point I feel like I'm probably already screwed. What I want to know is, LinkedIn says that they will not show your current company that you are looking, and my question is what risks are involved in that and how good is their privacy protection?

EDIT: Since it appears to be getting misunderstood, by setting my settings, I mean my job search preferences that get shared with recruiters; I'm not going to write on my profile in big bold letters "ACTIVELY SEARCHING"; that is, of course, ridiculous.