as a pest controller here in new zealand and although dont have any problems with termites, i have a few friends in aussie, i would suggest the pvc piping. its very popular in aussie and works a treat, u can always spray the areas of ur house....but the soil treatment is really what u need to keep in control.....
sorry not sure if u actually went ahead with the treatent or not as i am skimming some of ur articles.....remember its better to be safe than sorry.....i ahve customers that dont take my advise and i get them calling back...
great thread by the way....$320,000 nzd for ur house....not too bad