The difficulty I play at is somewhere in the upper eighties.(I hate the term "realism settings" in this case-a better term is "difficulty settings".)
Map contacts on, external view on-I like the purty pictures.
Like frau said though, anybody can tweek the files and play at 100% with everything unchecked if they want to. The advantage in that is you can get full renown credit for the ships you sink. IIRC, the renown for each ship is multiplied by your difficulty setting and that amount is credited to your renown.