These were my figures during the first month or so (haven't checked since)
VDSL Port Details Upstream Downstream
Attainable Net Data Rate: 17475 kbps 47156 kbps
Actual Aggregate Tx Power: - 16.1 dBm 10.3 dBm
VDSL Band Status U0 U1 U2 U3 D1 D2 D3
Line Attenuation(dB): 3.6 16.0 N/A N/A 8.8 19.8 N/A
Signal Attenuation(dB): 0.0 14.9 N/A N/A 8.8 19.8 N/A
SNR Margin(dB): 21.8 21.8 N/A N/A 10.7 11.4 N/A
TX Power(dBm): -28.6 -16.5 N/A N/A 9.5 2.6 N/A
So you can see I had SNR margin of around 11dB (average of the two downstream figures) when connecting at full 40Mbps speed.
The max attainable rate, reported by the modem, was 47Mbps.
The BT estimator (last week) guessed at around 60Mbps.
I had the 80/20 upgrade activated this morning and have an IP profile of 77.43Mbps (which probably means I'm connecting at, or very close to, maximum speed).
vDSL2 FTTC Infinity with BT
DL Sync 80Mbps
UL Sync 20Mbps