Oh dear!!, he must be very new, and not up on ADSL. There is not anything to choose between them (the BT and the ADSL Nation XTE2005).
When ADSL was an eng fit service, sometimes people were not too happy with the offical ADSL extension kit (it plugs in the ADSL socket of the filter) and used to ask if there was a neater way of doing it. Don't tell anyone, but the standard fiddle was to connect the extension to the incoming line (A and B on the master) and the all the extensions via the filter. Very naughty
