The point of the build is not to stomp the lane as hard (even though you can) the point is to have enough sustain that you wont be backing all the time so you will roam more, ultimate hunter helps with this by macking your ganks easier with ult, i dont think relentless hunter is needed(even though it will limit you to go from mid to bot and not so much to top) because you wont be roaming as much when your adc is in lane if not when he backs,also you can use w only on your adc so even when you are under tower mana wont be as much of a problem and fleet footwork lets you take bad trades without suffering as much(the heal is not much so it is not a get out of jail card). I dont think it is the best build but it fits my playstyle, it is a decent build, i recommend trying it.