It does help distribute the center of gravity towards the middle of the plane, it also adjusts the airflow as well, funnelling it appropriatly for stability. I used to think all planes needed it, only to find out, it's absolutely in the way when flying in any sort of wind, so I tend to completely ditch it with my creations. An added benifet for getting rid of it is that you do have more control since you aren't fighting the plane trying to make it's own adjustments without your input. You'll know you are ready to get rid of it when you no longer let the plane adjust itself, where you are correcting it before the plane has a chance to do it on it's own.