You also have to understand that when using a weighted float and a light weight jig ... you might not be able to detect a "lift bite", as when the fish comes up and grabs the jig but doesn't immediately go down with it. You wouldn't likely be able to tell the difference in the height above water of the float.
This is exactly the reason why FnF floats are off center weighted ... so that when the fish takes the weight of the jig off the float (lift bite) it will fall over. Were it weighted at the bottom, you'd never see the float move.