The advantages to this approach are manifold. Robinson is arguably the most physical corner on the roster, and that's a good fit against slot receivers. It gives Dunta a better shot at chipping in on surprise run plays, since he should have a better line of sight to the back. And it put Grimes and Samuel outside, where both really belong.
This is the approach the Falcons are planning to take, according to Comrade Dimitroff. He told Bill Polian on Sirius that Dunta not only fits inside as an aggressive, take-chances, spear-a-dude kinda corner, but that he actually wants to play the slot. You won't see a lot of controversy around this move, at least.
Given how often the Falcons are likely to trot out three corners and the emphasis they'll put on stopping some of the NFL's deadly passing offenses, you'll probably see this arrangement a lot.
Ultimately, this is probably the ideal arrangement for passing downs, at least in my mind. Do you agree?