Symmetrical modelling

I’ve always been using Mirror modifiers whenever I want to model stuff that is symmetrical about some axises, but recently I read of another technique for modelling symmetrical stuff, which is to use Linked Duplicates, as shown here at blender wiki. What are the benefits of using Linked Duplicates over Mirror modifiers, 'cause I’m slightly curious why Linked Duplis and not mirrors are mentioned… surely a mirror is easier to implement?

That’s how you used to have to do things in Blender before we got the Mirror modifier. It still works but, the Mirror modifier sort of encapsulates that process and adds the benefits and flexibilities that a modifier offers.

Linked duplicates was around before the mirror modifier. I think that particular page was originally written to help people do symmetrical organic modeling before the mirror modifier was written and has been over taken by events.

A practical use for linked duplicates would be in, say, architectural modeling, where you model a door mesh, and then use linked duplicates to create all the doors you need, but with the same mesh. So, if you decide to make a change to all the doors, you only have to manipulate the original mesh, and the changes show up on all the linked duplicates.

In this case the mirror modifier wouldn’t work, since doors may be at right angles to each other, and not be spaced at equal intervals from some axis. With linked duplicates, you can place each door anywhere, at any orientation.

Mirror modifier will be best for creating shape keys for different type of expressions.
I have used one software with this feature. You can select mirror syme. with X or Y or Z
It automatically detects the center point. If you modify on the center point, nothing happens but in the other vertix it takes effect.