Thanks for your input.
I have in the meantime managed to locate some more reviews, and apparently you cannot fight at all in Black Plague. All the reviews sound very positive, but I hate being completely helpless in a survival-horror type of setting.
On the other hand, I found the level of scariness quite managable with Overture, except that I hated the way your screen became distorted when your character becomes anxious. (Like a pulsing tunnel vision type of effect) It tended to give me a feeling of vertigo.
Does that also happen with Black Plague, Pokey, anyone?
If not, I think I'll definitely get the collection. If it does happen, I'll think on it a bit more.