OK, some graphs, although I think I might need a bit of help interpreting them.
Right,
Firstly the big red 'V' shape in your bit-loading & SNR graphs for the downstream D1 band looks very unusual.
It would be interesting to see the Attenuation & SNR values from --pbParams.
From the snippet you posted earlier, your Output power levels look a little low.
From that same snippet, your US SNRM level looks O.K. for the actual sync speed capped at 2000 k v the Attainable rate of 9261 k.
However, DS SNRM looks low for a sync speed of 32123 k v the Attainable rate of 41212 k.
On the rare occasions that my connection syncs as high as 32Mb, the Attainable rate is usually only around 33Mb.
It would appear that some noise somewhere is lowering your overall SNR & SNRM levels, thus keeping your DS sync speed down.
As DS band D1 uses lower frequencies (ADSL frequencies plus a bit), I wonder if cross-talk from nearby ADSL signals is the cause?
Also, your attenuation from the Hlog graph looks too high to achieve anything from the highest DS D3 band.
Bit-loading ceases at just over 70dB attenuation