I have a long running gaming group. We mostly play Pathfinder. We have tried some other games in the past, and I think the group is relatively open minded. We'd like to try a new system, specifically something that is not straight-fantasy. My first love has always been sci-fi. I have heard good things about RT, but know very little about it . I personally have almost no experience with the Warhammer/40K settings.
What are the big selling points for myself and my group? What would we enjoy and what would be a challenge to get into?