According to the Telecom Wholesale maps I live in an area of Takapuna that is not going to be cabinetised, so I'm assuming I'm going to remain connected to the exchange.

From my modem my line stats are:

Line Rate: 11027/953 (Attainable: 13484/953)
Noise: 11.6dB/11.8dB
Attenuation: 25dB/12.6dB

I live in the upstairs part of the house. The demarcation point is outside one of the windows, and early last year I had a line put in from this point, so the jack is about 2 to 3 metres away from the demarc point. All that is connected is a modem, no other equipment.

Downstairs is a splitter that was installed a few years ago. It originally was for broadband and telephone, but right now it's just the telephone that's connected.

I sync at about 9.5Mb down and 0.80Mb up, but I've read that if you divide the attenuation rate by 13.81 it gives you an approximate distance from the exchange, which for me is about 1.8km so theoretically I should be able to sync around the 18Mb mark according to this: http://www.internode.on.net/residential/broadband/adsl/extreme/performance/

I know it's probably hard to answer, but based on what is known, would I likely see a benefit that would make spending the $200 worthwhile?

Then speaking generally, how would anyone know if it will be of benefit to them? Will it be gauged on the stats the modem is showing or would someone need to come to the house first and take a look at the wiring?