Notes: I don't drink coffee, green tea once in a while, and minimal late-night stimuli (lights mostly off, no music, ...).
Before I started using F.lux there was an obvious taxing period around 1-2am where my eyes might have started to get blurry or headache would set in, assuming I had woken up and started working by ~8am. From there I would either go to bed or brute force the next few hours, despite being aware of the time in general. Now, I don't get that feeling until much later– either at 22hrs when the sun has come up and F.lux begins fading out, or a little later if I'm not paying attention until after the sun has come up and the screen's been blue for a while. (At that point, I either notice the sun through the trees or get a splitting headache).
To further describe where I work: shaded area, floor to ceiling books, no clock, no phones. I do graphic work during the day and by early evening I'm in the command line until whenever. I can usually get out during the day, but sometimes I just don't. I think the proper advice here would be to stop working at home while living in the city, but that's enough OT– I was simply pointing out my experience using F.lux!
I would imagine that any windows or external lighting is going to have a far greater effect than F.lux. I tried F.lux a while ago when it was recommended in a previous HN post but for me the only difference it seemed to have, was to make my computer monitor more difficult to read by making it too dim.
Also for me, my desk lamp automagically dims from 11 to 1pm, just to make me feel a little more sleepy.
Within two months, I had found a setting I felt comfortable at (right now it's at 3500K).
(Ubuntu user since 2004, OSX since about last year)
Tons of people with 3yo MBP's with an install of Snow Leopard, looking longingly at how pretty and useable my little powerless Netbook with 2GB of RAM is with OpenOffice/Dolphin/Blender/Gwenview/Firefox running and 40+ tabs open. They can barely run Safari, iPhoto, Mail.app, and Skype at the same time without constant beachballing, so they sit in quiet humility while I actually get stuff done.
Once installed on their computers, an install that just works, I grab AppMenu (QML) from kde-look and replace the default one. At this point the MBP owner has a better OS experience than Snow Leopard could/does offer, and we haven't even done any tweaking yet. like f.lux or redshift (which you can grab from a ppa). I don't see the crashes you guys do on these apps, oddly enough. just works for me and my customers.
I love you Mac guys, really. You pay top-dollar for your hardware, and then Apple forgets about you in less than 4 years. I almost feel like I'm a rescue worker for abused and battered Apple customers.
I am skeptical of your anecdote. My 2010 MBP was perfectly happy running Xcode, IntelliJ, and pretty much any other applications I'd care to run, and that was before I put a SSD in it (which, naturally, helped a lot).
I think you're stretching the truth by a great deal.