Hegemony isn't an imperial trait. The Roman Republic wanted to be a hegemon as well. As did the French. It;s an analytical folly to confuse any hegemonic instinct of being the top dog, with "imperialism".
The key difference is whether you seek hegemony, or whether you seek preponderance, but within a balance of power. The former is simply unsustainable, the latter is much more realistic (and realist).
Empires, due to a very narrow elite, are often far more restrained about foreign adventurism, as they have a better understanding of interests and because there's no need to deal with pesky public opinion most of the time.
Loading suggestions...