I did a lot of recruiting back when I was a corporate employee. One time, I attended a talk on the subject given by a brilliant manager from our company. He gave us several tips from his experience. The most important one, that still resonates in my head long after, was: hire the person that will take your job.
That sounds against the common sense. You have a good position, you worked hard to get to where you are. You have a family, a mortgage, you need to keep your job. Why on earth would you want to hire somebody to replace you?
The answer is simple: because someday you will want to move on. Someday, the opportunity will knock on your door. When it does, you want to make sure that you are not "too important" in your current position. You want to make sure that you will be able to walk away knowing that everything will keep on running smoothly.
Besides, in our line of business, you don't want to be stagnant. You want to evolve, to keep on growing. To learn new tricks. To feel young and hungry again. It is hard to do from your cushy position.
Go ahead and seek out that person. The one with the spark. The one that, once the interview is complete, you say to yourself: "this person will be able to do my job someday".