I have been using fogwash for nearly a year every day. I use £25 of gas every 4 weeks, but this is tax deductible.
Down side you have to have good hose connections as they will blow when hose gets hot. I did get this the first day or so, but not had any problems now for months.
Upside will do every thing cold will and quicker. Also removing cobwebs snail trails and those stubborn file black spots, also the frames clean really white, unless of course they are brown
We do a lot of 8 & 12wkly houses and it really does come into its own saving loads of time.
A difference I have also found is that if you are doing a conservatory and it has ice on the glass, if you were to clean with cold you would just make more ice. but with hot you gently warm the glass and ice and clean the glass. And because you have raised the temperature of the glass the window dry's before freezing again. And if it does freeze when the air temp rises it will run off as normal.
So would I get another? without a doubt.
Roy