The editor preferences work very well for me so far, except that I want to pull the line width setting further to the left than the 40em currently allowed.
The ideal for reading continuous text in English (paragraphs as opposed to scanning code or lists) is 10 - 14 words per line. At 40em this is more like 14-18 words per line, a bit too long for reading comfort. Increasing font size also increases line width (as the em is related to font size).
I think 35em would be perfect.