Well, Chorus has started work on the cabinet in our street (about 300m from the house!), so I've pulled the pin on Orcon and changed to Telecom.  (I'd had enough of slow international speeds in the evenings and during school holidays.)  I expected the line speed to drop, and sure enough, it's now about 4500 Kbps compared to 7500 with Orcon.

Is this simply due to the higher SNR that Telecom run compared to Orcon?  (12dB / 8dB respectively)  I note that the actual rate and the attainable rate are now the same, whereas with Orcon, the attainable rate was always higher.  Or does it also reflect equipment differences in the exchange?

Just curious, as we should get much higher speeds with a cabinet just up the road.