I got upgraded to 21cn in July and the exchange is using infineon chipset.
Currently using a linksys wag160n sync'd at 18.8Mb.
Also tried a BT Homehub 2.0 and only sync'd at 16Mb. Also tried a Thomson ST585 V6 which connected at around 13Mb at first and then just went crazy disconnecting all the time.
Attn = 25.5db
snr = 2.5-3.0db
Thinking about trying to get an infineon chipset based router to test like a dgn1000 to do a comparison.