The only reason I would get a better cooler for a 2700x is to let it boost higher for longer periods of time, assuming stock CPU settings. You will actually get more performance out of the chip if you keep temps low. That will stress motherboard VRMs a bit more and pull more power from the socket, so don't go that route unless you know your board and PSU can handle the extra load.
Of course if you are trying for a static-clock OC like 4.3 GHz, you will want the best cooling available within your budget. The 2700x will pull a lot of power at constant speeds higher than 4.0-4.1 GHz.