I think one of the big stories to deal with in a "Nice Borg" scenario is dealing with one of two problems: trying to deal with the Borg's slow assimilation plan (because they still plan on assimilation, only using advanced psychological and PR techniques) without causing a shooting war, trying to keep a "Britishin New Guinea" situation from happening, and at the same time keeping the hot heads who want a shooting war from causing one.

It would be more complex than your average TV plotline, but based on some struff I've seen recently, I think it could be done.