I think it is possible there is other life out there. I am not sure when or how we will discover it. The possible benefits are endless. To name a few, the possibility they could have the cures for many deseases we are still struggling with. I really don't think there is any real danger. After all if there is life out there, and it is so far advanced over our civilization, and they were hostile, I believe they would have already come here.
I have never thought about humans transmitting a beacon. That is an interesting idea. I will have to think about that one some more.
The reason I run SETI@home, is to help in my little way, to find out if there is any life out there. I feel the project is good, and we should keep trying to find out if we are alone in the Universe or not.