Very good literacy for "British Telecom" *rolls eyes*
As Andrew said, the 'claim' of better stability as absolute ...... and unless your line is actually capable of anymore speed or even much more its not exactly a major boost if at all.
Personally I would look at what offers are about on Black Friday for switchers...
Though getting a deal from BT would be recommended to save the havoc of switching and also they do seem to be the best performer although their customer service is somewhat lacking in any pride.
Dum Di Dum Di Dum Di Dum