What should US do?

According to Niall Ferguson, the British Empire was the biggest ever; at least it was in the mid-nineteenth and twentieth centuries. As Americans—products of the British—we should care about the Empire and determine whether to shed or shoulder it. But many find only fault with the British Empire's former actions. From the Trans-Atlantic Slave Trade, to the evidence within the Declaration of Independence and the 'Star Spangled Banner', it is difficult to overlook the "bad" in the British Empire. Author of The Rule of Empire, Timothy Parsons, and even parts of Cooper and Burbank's Empires in World History condemn the actions of the British Empire in their chapters. 

Yet Ferguson's book, Empire: The Rise and Demise of the British World Order and the Lessons for Global Power, aims to make some important observations about British Empire to shed some light on it's positive aspects. He argues, quite well, that Britain has done the most to promote goods, capital, and labor, and to impose Western norms around the world. Using statistical information and business reasoning, Ferguson even poses that "there is reason to doubt that the world would have been the same or even similar in the absence of the [British] Empire." 

He does not deny that Britain committed wrongdoings; they treated their slaves and colonies badly, and their Christian missionaries were often misguided. But Ferguson does an impeccable job of trying to convince the reader that the British Empire did more good than harm. Within his conclusion, he even argues that many of the areas involved in British colonization resulted in better situations economically. 

To me, this seems to be a bit of a stretch, considering how brutally the colonies were treated. Still, Ferguson makes an interesting point and poses an important question. 

Much of the British mindset is focused on empire; for a long time, that was their mission. But Ferguson argues that Britain does not have enough fiscal or military resources to be the "international government," only the United States currently does.

Do you agree with Ferguson? Is the United States in a place to move from informal to formal empire? And if we are, should we?