Actually, there is a thread that shows how the M92 renders rather complex material, such as music sheets, pictures and mathematical equations. But after searching for some time, I cannot find it, so you will have to take my word for it...
I read lots of books concerning programming on the M92, some of them use colours. Even colored code is readable, although I must admit it does not improve the readability of the text. With very complex technical drawings that use many colours, the M92 is not a good option. Keep in mind it only has 16 levels of grey. If you have a drawing in which you need to be able to tell the difference between five different shades of green, for example, the M92 will simply not be up to the task. Then again, I have never encountered such a problem until now, although I tend to use the device several hours per day for academic use. With regard to physics and programming, I think you are on the safe side. Concerning books about biology, I lack the experience to judge their readability.
If you have a specifically nasty image or piece of text and want to be sure if the M92 fits your needs, send it to me and I will take a photograph for you.