You should definitely do it. If you cant handle maintaining a good gpa in an undergrad honors program, what makes you think you can pass medical school classes? Also, with how competitive things are, it would be foolish not to. Do you really want to be opening your final rejection letter and think sh** what if I would have done honors? Plus, if you get to write a thesis (I know it sounds bad) you get an opportunity to show initiative, intellectual curiosity, leadership, and sheer sticktoitiveness. Also, if there are other applicants form your school or if the honors program is otherwise known of, an adcom member may ask why didnt they?