For red-green color blinds the changes on the diffs are difficult to find. For not red-green color blinds red highlights the changes, but for persons like me can not see them skimming. About 8 % of the males have this deficiency, so a big amount of users is discriminated.
In the German Wikipedia a user found the solution to give changes a blue highlight. It would be easy the see for "normal seeing" persons and for red-green color blinds as well.
Have a look at: http://de.wikipedia.org/wiki/Benutzer:Matze6587/monobook.css