I kind of figured that this had happened, which is why I was just waiting patiently...
Do you have any information on whether this heat demand percentage will be made available through the public Web API, either immediately after the firmware update is installed, or at some point in the near future ?
If I remember right there is even already a heat demand field in the API but it currently always reports zero. If there are plans to add this information to the API that would be fantastic as those of us with custom graphing systems (I use both Domoticz and Evohome-munin) could update our graphs to plot heat demand as well...