Just my humble opinion here of course, but sometimes in a search for hardcore realism we lose sight of what makes a good game.
To be historically accurate in June of 1944 you would need to recreat a U-boat sailing and then being hunted mercilessly - and SUNK - by dedicated H/K groups before it gets a chance to do any damage.
As it is now things get tough - but the reality was an almost impossibilty of success.
For me an event like, "The system damage to the boat may not be discovered until you are well out to sea and may require the immediate return to base using extreme caution." would not be enjoyable.
But hey, to all of you masochists out there, ENJOY.
Barkhorn.