Some of the work Nevil Brownlee presented at the conference could feed into this. So could the NLANR AMP stuff (now many ISPs have this deployed again?). Even the nzdsl speed test stuff.
I don't know if there is a speedtest server on the WIX/APE, but if there were then you'd be able to get a good appreciation of how the different ISPs fared when it came to a similar service.
I've over 2 million tests done from NZ DSL connections (For National Speeds), and overall there is no real difference on average in speeds per ISP (Nationally)(For DSL users) (even considering where the speedtest server is @ Orcon). Regarding the Speedtest.net results showing Airnet #1 and ICONZ #2, as the overall stats are taken from every test done (even on faster connections), So they will be skewed on ISP's who have more tests done on Higher Speed Connections (Wireless,Fibre etc). International Speed for DSL users per ISP is a different story, but I don't have enough results for any conclusion. Thanks