Based on personal experience, if you want to maximize the tire life you should rotate as documented. Also, reduce the air pressure in the rear tires a few lbs below manufacture's recommendations.
Below is a link with some pictures of the tire wear if you don't rotate.
Front Tire Wear - Caused by Alignment Issue
Clearly, the front alignment has some issues when shipped on early 300c's back in May 2004. Also you can see the manufacturer's tire pressure caused the rear tires to wear excessively in the centre. I specifically asked the dealer not to rotate the tires due to my personal preference for balance of the tires. The original balancing from the factory is always best.
Downside, by rotating the tires you mask the root issues with the car's tire wear problems.