apples and oranges
regarding hot and cold water blending to become just right, reducing the offending temperature is often as effective as increasing the the flow of the water from the direction that will acheive that just right feeling. This inverse relationship becomes a crucial variable as there is typically a limit of the amount of hot or cold water that can be dispensed at any given time due to the size of the valves, water pressure, the max and min temps available. On the water baloons and knives mix, I suggest first try hot water baloons mixed with a prudent dispersal of cold water baloons before taking the knife/water baloon hypothesis to the laboratory for testing.
Posted by TT Tom