It may not be an issue for anyone else, but always has for me, and that's the brightness of the crosshair when shooting long distance, especially in a dark area. A good example of this is when on the Temple level, trying to shoot someone the other end can be very difficult due to the crosshair blinding you from seeing the target. I have lowered the saturation and brightness of the crosshair to combat this personal issue and thought I would upload it for anyone else experiencing the same.
New Crosshair...
Download Link:-
http://www.mediafire.com/download/sahpayynnqt7x5v/Crosshair.zipInstallation:-
Extract the archive and place the "crosshair.vtf" in the "Steam\steamapps\sourcemods\gesource\materials\sprites" folder and click yes to overwrite. I have included the original as backup.