I dont see the point of a like button on a forum, it just removes the aspect of higher discussion. If I wanted to have conversations with a like button, I'd go on twitter or facebook. But no, I want to have conversations with people, friends I know, and other friends I dont know as well yet. I cant get to know people I dont know yet if my only interaction with them is them liking a post I happened to have made a week ago, instead of responding with a well thought out (or less than well thought out as the case may be) comment.
Like buttons are the tools of the lazy who dont want to take the time to think out an actual response, and I feel it is detrimental to a discussion board to implement a system that discourages conversation.
And if we are already worried about peoples feelings and reactions to this system should they not end up getting the likes and reactions they are hoping for, I can only imagine how bad those reactions and feelings actually will be should this system be executed.
All in all, I feel a "like" system is a bad idea, because it fails to add anything to a discussion topic and for the potential for drama that may arise.