It's evident from one of those Info-people from the bar that the Corsairs keep Gamma a secret through the use of force. Anyone leaking the location of the jumphole would most likely die a horribly accidental death.
"What? What's Gamma ... Never heard of it."
"But you can see the Jumphole from the window..."
"I NEVER HEARD OF IT!"
My vote gets the Cambridge -> O 5 -> Theta route, as it doesn't go through any guard systems, or any forbidden systems. Also, from the bars around Cambridge, it seems as though the Brets don't know exactly where the Jumphole is, but they know it's inside the ice cloud.
"The thirteen saloons that had lined the one street of Seney had not left a trace. The foundations of the Mansion House hotel stuck up above the ground. The stone was chipped and split by the fire. It was all that was left of the town of Seney. Even the surface had been burned off the ground.
Nick looked at the burned-over stretch of hillside, where he had expected to find the scattered houses of the town and then walked down the railroad track to the bridge over the river. The river was there."
