Do Weight Distribution Hitches Matter much?

Yes you need the WD hitch. No it will not help MPG. But there are things much more important than MPG. The ability to control the trailer under adverse conditions can be life and death situations. The WD will help in rouge winds, large trucks passing when you do not expect it, idiots that will pass you then decide to exit the freeway and force a panic stop. The WD will help you stop in a much shorter and controlled manner. When you brake heavy your trailer transfers a lot of weight to the truck rear end. This takes weight off of the front tires of the truck where you have much of your braking effort and steering control.
also recommend you get the best brake controller you can and would consider a P2 the minimum. Do not go cheap on brakes, brake controls or tires.