I would say somewhere between those 2 choices.. as I don't think it should have to be near accurate. But I do (normally) want it known that this is actually based on a true story. Like from your post... before now I would have never known that Silence of the Lambs and Psycho were inspired by Ed Gein.
I went over imdb to see what all I had from their list... had several I didn't mark before. Some of them I was like well No Shit! I knew that!
and others that kinda surprised me that they were based on a true story...
My List:- Amityville Horror (1979 - I know is based on a Hoax... but decided to keep it anyway)
- Amityville Horror (2005 - I know is based on a Hoax... but decided to keep it anyway)
- An American Haunting
- Deranged (haven't watched this yet)
- Erin Brockovich
- The Exorcism of Emily Rose
- From Hell
- Girl, Interrupted (this one surprised me)
- K19: The Widowmaker
- Man on the Moon
- Patch Adams
- Pearl Harbor
- Saving Private Ryan (never realized)
- Star 80
- Swearing Allegiance
- Ted Bundy
- Titanic
- Jack the Ripper
- We Were Soldiers (never realized)
- Zodiac
I will probably eventually do a weekend movie marathon of this some time... but probably nothing more then that.