I've personally had access to BRAT for a few years now. Alas, only on ADSL profiles ...... it is not available on my GEA profile.
I would hazard a guess you are correct with regard to BRAT being used on BT classic circuits, but we have to rely upon the CP's
own version of BRAT when looking at DSL fault history, (We request that they send over a data-pack).
BRAT has gotten better with age, it
used to summarise all its findings as REIN in a lot of previous cases, but when the attenuation graph was perused it was obvious a HR was allowing in unwanted 'Noise' that BRAT hadn't picked up on.
Now though, it does for the most part recognise if there is a potential 'HR' or similar network issue, (wet joint etc).
You can never, ever achieve a better test than a man in a van turning up at your door and running thorough tests, but I have to admit that the graphing data available to us, is far better of late.