[C#] Explicit Typecasting - ( ) vs "as"

One thing that confused me when starting out, was the seemingly intangible difference between typecasting via ([type])object and object as [Type]. With a small amount of digging here is what I found.

Two Methods of Explicit Typecasting

(1) "( )" Operator http://msdn2.microsoft.com/en-us/library/0z4503sa.aspx

- Will raise an exception if the typecast is not valid.

- Seems to have slightly more overhead in execution time [(1)][(2)]

- Works well with classic value types [int, double] [(1)]

(2) "as" Operator http://msdn2.microsoft.com/en-us/library/cscsdfbt.aspx

- Will return null if the typecast is not valid.

- Seems to have slightly less overhead in execution time.

- Only works for reference conversions and boxing conversions [(1)]

* Note: I believe the following is "boxing":

int myInt = 4;

Object myObj = myInt; // <-- now myInt is boxed into myObj.

int testInt = myObj as int // <-- can do this with as operator.

References:

(1) http://coercedcode.blogspot.com/2007/09/c-using-as-typecasting.html

(2) http://69.10.233.10/KB/cs/csharpcasts.aspx