On accuracy ... The shortest distance between two points is a straight line.
It is also the most accurate. So how does this relate to whips?

Well, this is how it breaks down.
It's all a matter of Calculus.
Calculus very basically having to do with segmenting an arc or circle. The smaller the segment the finer the arc. While whips do travel relatively "in line" in what ever plane they are traveling in. Whips as we all know also travel in a sinusoidal wave. This means that they create a loop down the length of the whip until this loop terminates at the cracker. So the problem then ... with regard to "pin point" accuracy and making a tight grouping ... is how to get this loop as small or as fine as possible thus approximating a straight line as much as possible.

The disadvantage the signalwhip has with regard to "true" accuracy is in fact the braided in cracker. Do to the fact that the cracker is braided in the whip becomes tighter and carries more mass and is less flexible where the cracker is joined to the whip, thus creating a large segment in the arc at that particular point. This is not conducive to creating a nice tight loop. When the loop travels down the whip and gets to the junction where the cracker is braided in it flops to a certain extent do to the added density and lack of flexibility. This creates a wider arc which causes the cracker to float and thus makes it less accurate. Now when you add a fall you are adding a piece of leather that is far more flexible than the thong of the whip its self so when the loop in the whip gets to the fall instead of widening the arc it actually tightens the arc reducing the amount of float and making it far more accurate. Contrary to popular belief the knot where a fall is attached to the thong of the whip has far less effect on the flow of the loop than a braided in cracker for all of the reasons I have already stated but also because this knot presents a much smaller segment in the arc than the junction of the cracker on a braided in cracker which is typically 4-6 inches long. This is why when you compare a snakewhip to a signalwhip you will find that the snakewhip is more accurate than the signalwhip. They are basically the same whip with the exception of the difference in the way the crackers are attached.

Also contrary to popular belief a shorter whip does not necessarily mean it is going to be more accurate. For instance a 4ft. signalwhip will never be as accurate as a 6ft. bullwhip because the 4ft. signalwhip cannot make as tight a loop as the bullwhip can simply because it is too short for the loop to develope. While the 6ft. Bullwhip has enough length in the thong to develop the loop and allow it to get smaller at the cracker.

Oh and one last thing on the effects of signalwhips with changeable crackers.
It never ceases to amaze me that the same people that say it makes no difference in whip performance to have a changeable cracker on a signalwhip will then go on say that they change the cracker to a different type to get different effects like cutting targets or putting out candles or being softer on their play partner. By doing this they negate the whole Idea that the changeable cracker has no effect.

I may be just splitting hairs here but thats just me I am anal about this stuff.
Just as I am anal about the way I make my whips.

Of course you don't have to take my word for all this.
You can do the calculus your self.