Component Class Hierarchy

Yes it is possible in c#

 SuperClass : MonoBehavior
 {
   ...
 }
 
 SubClass : SuperClass
 {
    void Update()
    {...}
    //etc.
 }

It should also be possible in UnityScript that way:

 class SuperClass extends MonoBehaviour
 {
     
 }
 
 class SubClassA extends SuperClass
 {
 }
 
 class SubClassB extends SuperClass
 {
 }

Note that every class have to be in it's own file and the file name has to match the class name. Otherwise you can't add the scripts to a GameObject.

I use C# exclusively because i don't like the JS-syntax ;) Also C# allows to inherit from one base-class and from additional interfaces whereas UnityScript only allows one ancestor. Also i don't have a clue of the virtual / override syntax in UnityScript which is actually one of the most important things when you use inheritance.

In C# you would do something like that:

 public class SuperClass : MonoBehavior
 {
     protected virtual void Update()
     {
     }
 }
 
 public class SubClass : SuperClass
 {
     protected override void Update()
     {
         base.Update(); // call the inherited function Update() from SuperClass
     }
 }