It does reduce some of the tongue weight, but TH's typically have the axles pushed farther back, so you really need a fat heavy toy pushed all the way back to see any change in tongue weight. The biggest change you will see in tongue weight is whether your tanks are full or empty since they typically sit over the axle or forward of it.
My Weekend Warrior had two 75 gallon fresh tanks and two 50 gallon waste tanks. one fresh tank was over the axles and the rest were forward of it. I was able to negate some of the tongue weight by keeping my 40 gallon fuel tank full which sat rear of the axles.
