Question
I live on a sandy barrier island off Florida's Gulf coast. Most people in our subdivision have driveways made of shell - compacted from car traffic. Do brick pavers set on sand improve the water drainage down into your own yard, or do they increase runoff into a neighbor's property or into the gulf via our roadside drains? Or are the two about the same?  

Answer
Any kind of paver will defenitely increase run off compared with compacted or crushed shell.
You could consider a permeable paver design which will cause less runoff than standard pavers.
However, it is unusual that storm water would be a significant issue on a barrier island. The soil is almost pure sand and very rarely does any water actually make it very far before it is absorbed by the sandy soils. When was the last time you saw a sheet of rain water flowing across a beach?  In any case, If you pitch your driveway grade from side to side, making it higher in the center, instead of sloping onto the street you should not increase any runoff outside your lot.
Best of Luck
Sean Murphy