Is the sentence, "this much we know", a short saying of "This is as much as we know"? Which one is formal?

Question

Just as the title above. Is the expression of "This much we know" kinda of more colloquial？

Answer 1

No it isn't.

"This much we know" - we know this for certain. Its conveying certainty.

"this is as much as we know" is a little different.

It's hinting that somethings are unknown.

Answer 2

'This much we know' is more appropriate. It does not sound just conversational, but professional.

Answer 3

"This much we know" is like saying "we don't know much about this subject, but here is what we do know".

"This is as much as we know" has a different meaning.  It's not that one's more formal than the other: they'd be used in different contexts.