I'm about 600m from my cabinet following the likely cable path. When first installed I got the full 38/10 and after the speed upgrade 56/20. A couple of months back someone on my street had it installed (and Openreach kindly disconnected me for a few hours whilst they installed it) and it plummeted to 32/20. Now that the Xmas lights are in people's gardens I'm seeing 25/20 at night. BT adsl checker says I should be seeing 58/20.
Basically from my experience it starts out great and as it becomes more popular it just nosedives.
(Speeds I quote above are the IP Profile for my line according to the BT Speedtester - throughput is usually ~1mbps lower downstream and ~5mbps lower upstream)