I've been an officiant for a few years now, since I was first asked by a friend to remarry his parents.  His Dad was sick then, and I was his hospice nurse.  I've never regretted this decision.  I think I was born to do this--to host a sacred ceremony of love.  Your officiant has to get it right the first time, to set the mood, the vibe, the tone of the way your ceremony will be remembered.  This is no task for a clown, or a person who isn't genuine.  You need someone who can help rachet down your stress, and if you get tearful or lost, can guide you on your biggest day.