I have heard that if we change GS-150 stock (the diaphragm type) carburetor with float type carb, like we have in CG-125. We can gain a much more sharp pickup and acceleration.
In float type, the throttle-set is directly in control of a user, the wire which is connected at one end to the accelerator and the other end to the throttle.
Where as in diaphragm, the accelerator wire is connected at one end to the accelerator and the other end is connected to a butterfly. Here when rider twist the accelerator, it opens up the butterfly which then result in the throttle opening.
For easy reference you may see below the difference between the two.
This is all my assumption that indirect-throttle-control limits the pick and the sudden acceleration. Which results in better economy.