Its not that hard to do the math to figure out what load your system can handle. If you have a home with aluminum wiring don't do it. Its really quite simple to wire a house you just need to do a little research, maybe buy a wiring book from the hardware store.
Have completely rewired a couple homes during the remodeling and its not that hard. The inspector comes in either approves it or he doesn't. One of the things you find out in the process is there really are no codes for wiring, onlu inspectors personal opinions and they all vary.