I tend not to believe the dark forest scenario. I think aggressive, exploitative, colonising tendencies lead to the extinction of a species before they can be exerted on other alien species. It also doesn't make sense to cross vast distances with invading armies for resources that aren't scarce in the universe. Advanced aliens will likely be largely cybernetic and by becoming so, leave animalistic behaviours behind - so not like the Borg at all. Perhaps I'm overly optimistic. I found this interview with Martin Rees regarding advanced aliens interesting.