The Full Cheek cheek piece, will have the same effect as the traditional Eggbutt in so much as, it will prevent pinching on the sides of the mouth, however the extended pins above and below the bit, firstly prevent the bit being pulled through the mouth and secondly have the effect of guiding the horses head which is great for schooling and training purposes.
The Waterford bit has many smooth flexible bumps or bubbles, which spreads the pressure over many points making it a light mouthpiece. The greater flexibility discourages a horse from leaning on it.
The Waterford bit is a good choice for a horse that leans, it also promotes mouthing and salivation. The Waterford is usually worn ¼" - ½" longer than your traditional mouthpiece in order to curl around the lips and maximise the effect.