Multiple PSU or one big one?

Right now I have 4 GPU + MOBO and 5 fans running off a single 850w Seasonic GOLD rated PSU. I dont like how the psu is getting warm to the touch now. I ordered an extra 650w to help power 2 GPU while the 850 will power the MOBO + 2 GPU. Is it better this way, or better with a big 1000W + PSU. Pros? Cons?