I have code that references a web service, and I\'d like the address of that web service to be dynamic (read from a database, config file, etc.) so that it is easily changed
If you are truly dynamically setting this, you should set the .Url field of instance of the proxy class you are calling.
Setting the value in the .config file from within your program:
Is a mess;
Might not be read until the next application start.
If it is only something that needs to be done once per installation, I'd agree with the other posters and use the .config file and the dynamic setting.