Just had an upgrade from ADSL to FTTC so I'm currently on the basic 40/10 profile. The engineer said the line was only running at 29% speed capacity so there is definitely a benefit to be had from upgrading to the 80/20 profile as the line can theoretically support 38.7 mb/s up and 137.8 mb/s down according to the line tester (see pic) 
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FTTC Install
date: thu 25 apr 13