2wire 2700HGV attenuation figures

[#1]

Are there any 2700HGV experts here? Looking at the DSL Diagnostics page on my router, I can view two sets of attenuation figures.
The first is at the top of the page:
Downstream Atten. at 300kHz: 66.4 dB
The second is further down in the more detailed information:
Downstream attenuation 72.6 dB
When talking about attenuation, is it common to use the (@300kHz) figure or the "other one"? I realise that both figures are high, but 72.6dB seems ridiculous compared to what other people report (yet I get around 2000kbps sync with 6dB SNR). I have more than one 2700HGV and they all report the same figures, so I don't believe it to be a router fault.

[#2]

99% of routers wont actualy report anything above 63db so even if it is 72db the router will still say 63db the 2700 is one of the routers that tells te truth
However that said,some numbers just dont match up there you should not be able to sync at 2000 with that sort of attenuation BUT your SNR Margin is a hell of alot lower than I would expect to see also.
Its a puzzle this one.

[#3]

Most routers only report the second form of the attenuation , the calculated one. This is calculated across all the used frequencies and ( since attenuation increases at higher frequencies ) is higher than the basic attenuation of the physical line at 300Khz. The 2700 is the only one I've seen that actually shows the basic attenuation. Mine for instance is 27.5db at 300khz but the calculated one is 30.8db.
2700's are particularly good on long lines, so I'm not too surprised you manage to sync at 2000k with a basic attenuation of 63db, I've got a friend on a similar length line who manages about 2000k.

[#4]

My understanding is that on maxADSL/ADSL1 attenuation is designated to be the value at 300kHz; however on ADSL2/ADSL2+ attenuation is an average value across the frequencies, which for the reason explained by MisterW, can be a few dBs higher.

[#5]

Not sure about that spraxt , I'm still on maxADSL(20CN) and as above , my calculated attenuation is different to the 300khz figure.

[#6]

In the absence of any other info that I can find, I've always assumed that the 2700 reports the 300kHz figure as a kind of benchmark, which will hold true no matter what's happening in the bins.