Same here in Italy. Also, thermostats will turn of and on the main heater based on the temperature detected where the sensor is, that is, typically, the thermostat itself. Water temperature runnign into radiators is usually 55 Celsius degrees, here, but that is adjustable on the heater and never changed for the entire life of the system. So, yes, in such systems that is a "dumb statement". Temp you set on the thermostat will not affect how quickly heat is tranferred to the air in the house.

I've recently heard of some friends using the AC systems as heaters in winter (they all come with such feature). They all report not being particularly happy with such solution. Having hot air blow into rooms is usually not so pleasant, altough I suppose that is subjective to some extent. Noise is another complaint, if you're not using a good and quiet deivice. But, the biggest complaint seems to be that when you power it down temperature tends to drop quicker, mostly because radiators take more time to cool down, of course.

I particularly like the geothermal solution I've just learned about in this thread. I knew nothing about it, but it sounds actually smart, and makes so much sense.