My 2016 China built F-2512 has a single truss rod, the neck has relatively shallow shoulders, like a shallow D shape. My son's China built F-1512 from maybe 2 years earlier has twin truss rods and a chunkier neck with fuller shoulders (more of a full D with a flatter back). I would guess that the fuller neck is shaped to accomodate the twin truss rods, and that maybe twin rod necks tend to be fuller wherever they're made - is that correct, guys? There was a post somewhere here recently (sorry, can't find it) suggesting that 2000 - something USA built Guild 12s had a single truss rod with a carbon bar down each side, which sounds like it might enable shallower shoulders on the neck. Hmm, I'm not sure this helps much
Anyone played them all?