Geoff is near Childers, which is in southern Queensland. It is a temperate/sub-tropical climate, whose meterological details can be found at: http://www.bom.gov.au/climate/averag...w_039025.shtml
The climate there doesn't appear to be that much warmer than it is here in Sydney, a few degrees.
Interesting that Geoff finds lowland truncata more tolerant of cold than lowland. That is the direct opposite of my experience. My lowland truncata stops growing and pitchering in cold weather, and any pitchers which had been developing in autumn open stunted. My highland truncata plants continue to pitcher during winter, normal sized pitchers, and grow faster than my lowland plants in summer. I find the highland variety dead easy to grow. But everyone's experience is different.
Many, many Nepenthes species will grow in conditions in cultivation quite different from those in which they grow in the wild. Also remember that a fair few species have a decent altitudinal distribution, so are naturally found in varying climates. It appears only to be the ultra-highlanders, of which there are only a handful, than are temperamental. And many species listed as highland species are found at intermediate altitudes, so are not truly highlanders are such (but you can spend hours debating what "lowland, highland, and intermediate actually mean).
The other thing is, weather is seasonal. I've got Nepenthes plants that thrived for years, then had a few bad years, then came good again etc. That is because some summers are hot and wet, others are hot and dry, some aren't so hot but dry, autumn can be wet and dank, or clear and warm. My plants will react accordingly.
All I can say is - give it a go. You won't know until you've tried.