We have two of the cafaro ecofans, one on a conventional squirrel 5kw and one on a squirrel convector 5kw. There is now doubt they make a big difference and warm the whole house. Think I paid about £90 each a few years ago – seems like they are more now though.
Both have been well used as they are on (almost) our primary heat sources, however one has had a new motor fitted and is now displaying the symptoms of needing another one after a year. Would I buy another? I am not sure, there are plenty of cheaper fans on the market and the cheapo ones my friends have work fine. One in particular is on 24/7 and has been for years, no problem. The guy in my local stove shop sold various brands and didn’t think any of them were bad.
I always fancied the stirling engine one but they had disappeared when I bought mine, Think they are available again though but I am not sure they are silent from the ones I have seen/heard, if that matters.