Thanks for developing this - I've been a happy user for about a year. That said, I've introduced a few non-technical friends to Redshift and they've all been really off-put by how extreme the default settings are. Because the GUI doesn't support configuration, they've turned it off until I get a chance to edit ~/.config/redshift.conf for them.
I think a more reasonable option would be to leave daytime settings unchanged and to set the night-time color temperature to ~4500K.
Thoughts?