In our experience the DVS we installed in our previous house was without doubt THE BEST money we have ever spent. We had floor to ceiling windows in the lounge just running with water and within two days it was all gone to never be seen again.
So I find it very hard to believe it when people say PPV systems don't work in NZ climates !
We ended up insulated in the roof, under the house, removed the old woodburner and installed a heat pump but the DVS was faultless.
Now were in our new place and were going through the same thing (another 1960's home). We have a wood burner pumping out masses of heat into one room and it goes nowhere else. The four bedrooms have simple panel heaters which take the chill off but little else (as expected).
So were about to pull the trigger on another DVS.
HRV are much more expensive and the sales bloke couldnt tell me anything other than 'we are the best'.
Our local council offer a 'review' service but his advice was fine for a new build, which was to shut up shop with double glazing etc, but how on earth to you plug every hole and gap in a 50 year old house. Its just not possible.
I'm looking forward to reading this thread to see what other experiences are.