My primary rig these days is a treble off the belly and a single off the tail. I like trebles and I don't subscribe to the theory that you catch more fish with singles.
I don't doubt that you drop a higher percentage of fish with trebles but I also don't doubt that the hook-up percentage is higher. If you know how to keep the pressure and tension on, you won't drop many fish.
The fact that we use barbless hooks contributes to this. That is a completely separate argument but I strongly support the use of barbless hooks for GTs. I don't want to start a debate but to me, if you intend to C&R, I believe it is irresponsible to use barbed hooks especially on fish like GTs which have a high escape ratio. There is a strong likelihood that any fish that escapes has been condemned to a slow death. I actually don't use barbs for any type of fishing these days.
I use a single off the tail because I cannot deny that over time, I have seen that trailing treble cause a lot of damage on fish as it swings around. The majority of GTs are hooked on the belly hook so the tail hook tend to swing around.
On smaller poppers, I often use just a belly treble. There is a reasonably well-known GT fisherman who fishes internationally who only uses a small belly trebles on his poppers like a 3/0 or 4/0. The reason is he wants to cause minimal damage to the fish. He drops heaps of fish but he is happy doing that.
The Baker rig which we use has been primarily driven by Nomad Sportfishing's abolishment of the use of trebles. It's a good but fussy set-up. I use these off the belly primarily with a single off the tail.
The big Japanese poppers have been designed to be used with a big treble like a Decoy 10/0 or a Gamakatsu Recorder 8/0. That's not to say that you can't use singles on them but they have been designed to be used with big trebles. You'll find the recommended hooks on their websites.