4 Year old Thread here, but - The question of 4 fletch vs. 3 fletch isn't that simple - the answer is "It Depends".
You can shoot a low profile, short vane fletched 4 fletch with a 1 degree offset, and get LESS stabilization than a longer, higher profile 3-fletch with a big helical... Or, it could be the other way around depending on the choices you make. It's all about lateral surface area of the vanes when it comes to horizontal wind drift, and frontal surface area and the drag and rotation that induces when it comes to stabilizing the arrow.
And, Shane's right. If you're a better shot with a well tuned bow (People like Shane, Gillingham), you need less stabilization than someone who's not as good a shot and torques the bow more often (Me), or who has a bow that isn't as well tuned. Fixed blade vs. mechanical plays in here too.
Best thing you can do? Try out a bunch of different combinations. Test them with broadheads shooting at paper targets - chart your accuracy (consistency) and how much drop / drift you get, then use what works best for your setup, because it may be different than for someone else.