Buy RC2 when the job is eight zones or fewer and you want Wi-Fi in one SKU. Buy ESP-TM2 + LNK2WIFI when you want Extra Simple Programming and may add the app later, or when you need 4, 6, or 12 fixed stations. Do not add LNK2 to an RC2. Move to ESP-ME3 if the site will grow past the fixed count or needs FG100 flow.