The classic pear lead will cast a very very long way, almost as far as the Distance Lead and it is less affected by cross winds because the shape is very condensed. This means the Pear lead is suited to most carp fishing situations when fishing anything up to the very limit of your casting ability.
The dumpy shape can be used to your advantage in silt, try using a very light pear lead say 1oz or 2oz and actually let the lead plug into the silt, this will dramatically increase the resistance to a moving carp so what feels like a light lead in your hand is transformed into a heavy lead in the fishing situation.
Because the lead has a large rounded end it makes 'feeling' the lead hit the bottom easier than more slender or pointed shapes, if you are new to this technique this lead will make the job easier.
The pear lead is also ideal in a solid PVA bag because it can be pushed down into one of the corners. This makes the bag nose heavy and so more accurate.