Growl! Hiss! Snarl!
Spin is the 'exception'.
However... it's difficult to keep spin consistent, considering we're talking about gelatin balls here.
Inconsistent spin equates to inconsistent range.
And... inconsistent spin also has the negative side effect of inconsistent velocity. Reason being... conservation of energy. A finite amount of energy is used in firing the ball (since you chrono your gun and it shoots roughly same amount of air each time). That finite amount of energy goes towards the ball's horizontal velocity, and/or its spin.
Total Energy to shoot ball = Energy of velocity + Energy of spin (which varies).
Basically... more spin = less velocity... and vice versa.
The negative side effects of a backspin system result in lessened accuracy. Positives: Some range advantage, flatter trajectory.
The whole purpose for greater range is to be able to hit people easier. A less accurate gun makes it harder to hit people, defeats the purpose don't it? A backspin system basically gives you a chance to miss people you couldn't hit in the first place... and miss people from closer ranges you would have hit without the backspin system.