To be honest I like both ideas and think both could work as a definitive role for Duke.
I really did like the direction Patrick was headed in with Duke being a daytime protector and there are no Bats working in Gotham during the day so it's a niche that hasn't been filled yet. I don't see it as necessarily being something that keeping him distant from the others but rather as some that might allow him the wiggle room to become his own hero without having to struggle with being in the Bat's shadow like most of the Robin's do. (I'd seriously like to see this idea developed further by Patrick at some point.)
The black ops idea has merit as well though and I do think that's the direction Outsiders will go in. I think such a direction would really expand his skill set for starters and would put him in contact with a whole host of characters from around the DCU rather than just members of the Bat Family. I also think it would give him a wider range of experiences that he can draw from than simply sticking around Gotham being it's daytime protector would.
My only issue with him as the black ops guy is that there are several other characters who could fit that role including Batman himself so the daytime protector niche is more unique. Doesn't change the fact that I think the black ops angle would add a lot to his character though.