Do you have the Dictionary of Intermediate Japanese Grammar? If so there is a detailed explanation in there :)!
Here is the outline of it.
(Sentence = S)
S ということ is used to represent a concept in the S rather than a fact.
S こと is when S represents a fact (or near fact).
But if it is a fact that the speaker knows by an indirect experience S ということ is okay.
Or if S is likely to happen, both are okay.
I think there is another point or two… but they have escaped my head.