Yes, triple clicking the home button will invert the colors, and I do that now as a poor-mans solution. However, it can be quite inconvienent when switching between apps and then always having to triple-click back and forth. Also, when there are links and such, it becomes a visual problem, or if you want to see a picture someone has. So as long as you never leave the app it works somewhat okay, but eventually you have to switch it back everytime you leave the app. That being said, the fact that people use the triple click feature now just emphasizes the need for the feature.
It is somewhat common in many apps that are heavily reading-centric for there to be two apps available, a free one, and a paid one. The paid one almost always has a low-light/night mode. Like I said, I'm more than willing to pay for the feature, and I think there are many people that would do it as well. For most people that use a low-light mode, they use that mode all the time, not just at night becuase it's easier on the eyes, even during the day. For the ER app, it opens into a white page, which is just blindingly white, and there is so much white color in the app everywhere you navigate that is strains the eyes after a very short time. I just think it'd make the app more appealing to almost everyone.
