I can think of two more case-study examples of the benefits of colonialism; India and The American Colonies.
First, India, while being ruled as a part of the British Empire after the disasterous Sepoy Rebellion, experianced an unprecidented level of industrialization and infastructure investment, mostly contributed by Britain. Railroads, telegraphs, roads, powerplants and mills were all build by the British, and when Indian achieved its independence in 1947, they kept all the infastructure. The first schools and universities in India were also built by the British, and many Indians admitted these were all good things.
Also, the American Colonies in 1755 had to fight a very long and devestating war with their old advasaries, France. The British Army, came over to North American and absorbed most of the cost and casualties that ultimately removed the French from the New World and allowed the Americans to spread west.
These are positives, but may be outweighed by the negative factors.