[jessedhillon]

In my experience, most validation on the server is a superset of what's required on the client (or disjoint).

For example, validating a user's name on the client merely checks if the name's length is in a certain range and doesn't contain invalid characters. On the server it requires a query to the database -- possibly more.

I also reject the notion that there is a significant context switch involved in going from one language to the other.