No, but then I don't understand the imperial incentive, even here on Earth. I'm a fairly self-centered individual, and a lazy one at that... and as far as I can see, running an empire always seems to be more trouble than it's worth. The whole history of the twentieth century can be written in terms of the world's great powers discovering this little tidbit of truth. I believe the first few decades of the twenty-first will see the US experiencing the same global comedown that Russia, Germany, and Britain have already undergone.

Fortunately, the loss of its empire is a process that always seems to leave the nation in question better off, at least in modern times. As I see it the only possible justification for total galactic conquest is self-defense: do unto others before they can do unto you, more or less as you put it. Any advanced civilization that doesn't see that as a self-defeating justification is so different from my way of thinking that I couldn't possibly deal with them on any terms, offensive or otherwise.

Basically, what you're saying is that the only way to survive and prosper in the Universe is to be a murderous, psychopathic douchebag on a galactic scale. Not down with that, sorry.