Jeff and others,
What the divider plate does, is reduce the size of the carb at the first half of the throttle opening. In effect it is like having a smaller carb which in turn makes the pilot circuitry more sensitive giving better throttle control.
This does give the bike more control at lower throttle settings. Once the slide passes the divider plate the carb just gets bigger and bigger as the throttle opens. This lets you have the same power delivery at WOT as it did before.
Boring a carb will give you better performance on the top end, but will reduce the low end sensitivity.
So a
carb mod such as boring and installing the divider plate will give the benefits of a smaller carb on the bottom end and the benefits of a bigger carb on the top end.
Ron