Where do you stand on Map Updates?

[siber]

Hi all.

I'm playing regularly now and, although in 1939/1940, am getting quite successful at high realism (as shown in tag). However, I'm generally pulling in 20k+ tonnes per patrol, sinking between 4 and 6 merchants each time out, and am wondering (in the name of 'simulation' rather than 'game') about knocking realism up to 100%.

When I try this though, I noticed that I got 100% realism WITHOUT map updates disabled - it makes no difference to the realism settings whether map updates is on or off.

If I turn off map updates though, I'll only be able to find ships that the crew see or hear. Contacts won't be plotted on the map as if reported by BdU or after being spotted nearby by (simulated) other friendly subs or aircraft, right?

So which setting is best for realism? Map updates off, but losing updates which might have really been reported by friendly assets that SHIII can't simulate realistically? Or map updates on, but fed far more information (range/course of targets and ship size etc) than would really be available?

What do you all think? Any comments/thoughts appreciated!