Re: F.Lux
I have been a long time user of F.lux, in most cases it's use is highly beneficial in reducing eye strain and reminding me it is probably time to sleep (I actually start to feel tired not bathed in bright blue).
Anyway as MD Rackham says do not do anything that relies on color correction, I know that most people who know about CC will know about that but I have found instances where just in normal work you need to hit the Disable .. for an hour (or until sunrise) menu options. These include working on mail threads where people have used color coding to identify their comments. All of those subtle colors look very similar with such a big shift in gamma.
(OK so that was freaky as I typed the last sentence I could feel my world changing as my screen slowly reddened as it must be an hour ago since I disabled F.lux as I worked my way through a large color coded mail thread).
So what about QS? Almost the first thing I install after the OS. I know that Alfred can do some of what it does bit it is the best launcher available for OS X.