Well, remember that this Orin is a bit different to the comics, and he's in Gotham for a specific reason, so he'd only stay with the team as long as they were pursuing the same goals he was. He'd crop up wherever he was needed, but for the most part he'd be doing his own thing. I see him bouncing between Gotham and Metropolis, depending on what's going on. Nightstar I think would remain staunchly in Gotham, for a variety of reasons that are different levels and varieties of twisted and normal both.