My reasoning is the color temperatures are adjustable in the indicator applet. Additionally, it doesn’t require geoclue to find location on your IP address. All you need to do is enter your coordinates or zip code and it sets your location.
Totally personal preference. I just always have problems with redshift acting funny when you exit the app and it never seems to reliably adjust when it starts up.
AFAIK Redshift was never based on f.lux. Maybe in principle since Redshift has been called a f.lux for Linux , but Redshift was around long before a Linux client of f.lux was made.
Redshift adjusts the color temperature of your screen according to your surroundings. This may help your eyes hurt less if you are working in front of the screen at night. This program is inspired by f.lux (please see this post for the reason why I started this project).