That said I'm the kind of guy who'll happily lose a few Mbps for the sake of perfect stability. I don't 'push' a line with custom SNR or anything. Some people force to SNR as low as 1 / 2 db. Crazy in my opinion.

I found it perfectly sensible on an O2 LLU connection. Even as low as 0.5dB at connection time was useful to me. Stability was not my aim.

I didn't mind a few dropouts in the evening as I wasn't doing streaming. Just this sort of thing and browsing generally, so they were usually not noticed other than being aware of a change through RouterStats. The result was it always sync'ed higher than any stable setting, which was around 4dB. Error rates of all kinds were acceptable in terms of resultant performance, so it made sense for me .

Now back on an "IP-Profiled" connection, yes - it would be madness. I have tried a few tweakings on FTTC, with stable but confusing results. I don't recommend it.