I tried this in 3.7.4 and after rebuilding my post cache, the edit comments are still there.
It worked for not showing new edits, but all the old ones still show.
Should I try something different?
I am interesting in this too, becouse as I can see, there is no way to get rid of this in posts which already exists (I am not talking about new posts or about not showing this info for some usergroups in global).
There should be some option to delete this on specific older posts, not only to choose if you want to display it or not from now on :-(.