A surprising umber of my Evo customers have emailed me with savings, around 30% is not untypical.
And I've been using 16 zones since 2003 myself in my own house, so have practical long term experience.
If you haven't fitted one in your house, you of course have every right to be sceptical. However don't let your tardiness put off others unjustly.
It is easy to forget zoning simply makes your house much, much smaller. Of course it will be cheaper to run.
It wouldn't work in a house with every room occupied 24/7, but few of us live in such a scenario.
I was trying for unsure rather than negative and I'm not sceptical, I've just no experience other than installing a couple of systems years ago that I never got feedback from. I hope to snag some of our new stuff coming out soon that will allow me to zone in the place I am refurbishing at the moment but nowadays this is a different proposition with the ability to intergrate the sensors to one controller and then to the boiler.
Not doubting your experience but am fed up with advertised hype promising the world to customers and usually prefixed with the two words 'up to' which is unhelpful.