Hi Andrew,
i read a lot in this forum and i found very interesting posts for all the Heating thermostats you are looking for.
I also decided before one week to buy for my home a smart thermostat and i go with tado my decision for this was that it could be very good also as stad alone as it has a lot of feutures that can be programmed as smartthings for example has person location,also my decision was not to integrate with smarttgings as icouldn’t find a a very good stable dh and if it was i believe that smartthings has a lot of unstable situations to trust my heating as only integration with this.
Also i find very good reviews for Honeywell Evohome with very good integration and dh and i have read that it will be also an official integration for this but i suspect you have to wait wait and wait as we wait for many integrations.
Hope i help a little.
There is no smartthings integration with heatmiser apart from either creating a jump server or using IFTTT. The reason is mainly because there’s no http API available for the thermostat, however there’s a campaign to try and persuade the vendor to create an api or provide direct support. Please lend your support here if you haven’t done so!