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Tado TRV types
I have both, and the only difference that I can tell is that with Smart SRT you will be able to have a graphic shown in the app in Air Comfort section, as you see in the image.
If you have a basic thermostat you will see the message that it does not support Air Comfort feature.
Both types collect this data but Basic is handicapped in software analytics. So, in my opinion, the price difference is not worth it.