Guys you've gone way off topic here
I see your point,
but the extension is partly related to the topic in that some of the advice given to mobanded was to build his own table, and if this route is taken the success or otherwise of extensions will determine the sort of router, insert plate or table top that is used.
Different table tops or inserts are thicker than others and need an extension to allow successful use of certain cutters, and different routers have different plunge depths. If someone is looking to buy or make a top they need to take all of this into consideration.
What works for one persons needs does not necessarily work for others and someone looking to get into area new to them should be aware of all the options to achieve a solution so they can make an informed decision.