@neologist,
neologist wrote:
To be perfectly clear, "let me say this about that".
Oh no. You've split "note that" - the powerful idiom.
"Note that" is not an idiom.
"Note" refers to observing carefuly, noticing. "That,” as in your title question, also refers to the thing specified as follows. There is nothing idiomatic about the phrase.
“Take note” is an idiom, however.
