The Woolguard HFS-SFS1822-50 is indeed an upgraded version compared to the HFS-SFS1822-25. One of the key differences is its enhanced sensitivity and detection range, which allows for earlier detection of potential fire hazards. Additionally, the HFS-SFS1822-50 comes equipped with advanced communication features, facilitating quicker response times in case of emergencies. Overall, upgrading to the HFS-SFS1822-50 ensures improved safety measures and better protection for your property.