SS6 Dataset US or NM

I would like to upgrade from SS4 to SS6. Our current SS4 which was setup by our administrator who no longer works here is based on the US dataset. As we work in the metric system here in Australia I was wondering should I install the NM dataset this time. However the company I work for is American and we have been given imperial linestyles to use so my other option is to run with the US dataset and change the uom to metric.