I didn't read all of these post but balancing the load is why we carry two rear panniers instead of one. All of our stuff would easily fit into one bag but we split it so each bag is 50% full. That's per person. In the past we've used two full bags for the two of us and we switched days carrying the load. He'd carry the load one day while I rode empty and the next day I'd carry the load while he rode empty. We now both have two panniers each for the sole purpose of being able to carry extra food and water when needed but they're never more than 50% full.
Neither of us have ever tried front panniers and we probably wont ever have to.