Yes you can brake much deeper into a corner. They are adjustable front to back put to much front brake in can cause the rear to lift causing a loose condition. I know I have done it. it is not like a motocycle where most of the braking comes from the front brake.
Stopping distances are noticeably shorter, but it will take some mental adjusting to be able to use the brakes to their full potential.
When the brakes are properly adjusted the kart will stop much straighter than with rear brakes only. The driving technique is different because of this, though. Instead of a rounded entry as with rear brakes only, the corner is more diamond-shaped (straighter under braking, sharper mid-corner, and straighter exit).