I would think that, at 1Liter/day, there's no pro or con to the ORS. Think about it - we developed to drink water, not salt water. ORS isn't some magical potion, it just replaces electrolytes.

Lets say you're sweating like crazy. sure, you're losing electrolytes, but also water, so you're probably increasing the concentration of electrolytes in your body. Adding extra doesn't help (hypernatremia, anyone?)

It's hard to over-drink water at 1L/day, so dilutional hyponatremia is pretty low risk.

Final answer from me? why bother with ORS - wasting money!