As an owner of a DI car, I can say it works well... though it may not be the best for heavy modifiers...
With the Mazdaspeed6 as an example, the high pressure fuel injectors seem to support anything you throw at them, but getting a pump to do it is another story...
One benefit you didn't list is the fuel actually cools the chambers before it combusts
EDIT: Just wanted to add, on a Mazdaspeed6, Direct Injection seems to add a lot of sound, my wife has the same car (non turbo, standard fuel injection) and I can hear the car fire on the Mazdaspeed. If you pop the hood and listen to it idle, you can literally hear every firing of the cylinders...