I have always been a proponent of working in an area that I know very well.
I feel that the agent should be very knowledgeable about the local area so that they can properly promote a property. That being said, just because an agents office may be located a long distance away does not necessarily mean that they do not work and have solid knowledge in your area.
I recommend that you ask the prospective agent how many properties they have sold in your area, how accessible will they be to you should you need to meet or they need to show the home and how familiar they are with your town. Although I am not comfortable working outside of my core area I know some agents who can work effectively outside of the town where their office is located . I think that asking the agent a few questions about their experience in your town may help you decide if they are the right agent to market your property.
I hope this helps