What are the advantages and disadvantages of being a neighborhood specialist?

Hello All:

It is October and time I reflect and look at if I need to change any of my business practices.  I am in a very large geographic area of Jacksonville, Florida.  It is spead across 3 counties.  I am toying with the idea of starting to limit or specializing in certain areas of town.  I have covered the entire area and now have past customers who contact me from everywhere I have sold to them over past years. 

Could I get some positive and negitive feedback from agents who have specialized and others who have not.

How did you effectivily do an area specialized? 

Deal with competitors who are already strongly in a neighborhood? 

Any feedback would be greatly apprecieted.