I was pondering this.

I know that you cannot deactivate a component, though it does not get messages like Update, etc.

I was wondering because I have some behaviors that more or less act like data containers(like Transform/Renderer etc) but are unique to each GameObject and need to be edited in the inspector.

Obviously a Monobehavior can meet all of these needs.

Like my question asks, are there any editTime/runtime advantages to extending Component?

If your script does not have Start or Update method, then I will not get any call to Start/Update.

So I set up a test to see the difference, only to be told that you cannot attach a script that does not extend Monobehavior. Guess that settles it.