All things being equal (and with a tiny sample) the Quad outgrew the Manifold. Still drying the other Manifold and will post her too. But the Manifold was easier to grow. Easier to train. So I have two hypothesis; (1) That the the way to optimize a 4x4X6.5, with 600w to 750w is - Six plants properly grown with a manifold to get every watt in the sweet spot OR (2) That the the way to optimize a 4x4X6.5, with 600w to 750w is - Four pants properly grown with a Quadline to get every watt in sweet spot.
I have not decided which way works best for me yet - So next grow will be six plants, trained with a manifold grow. The grow after will be four plants in a quadline grow. (yes I am a geek and like measures and numbers)