Please change WP to use only relative paths throughout the system.
The code and all entries in DB should be site-independent. WP should work no matter what domain it is located on. If WP really needs to know the site URL it should be set only in one location, preferably in the config file.
I am considering to start using WP to develop websites, but the steps that are necessary to move WP site between Dev, Test and Live environments makes me hesitate.
I am not aware of any other CMS that has this problem.