Perhaps a way to have comments of agreement that can also work as signalling your own smarts would be to say that you agree, and that the best part/most persuasive part/most useful part is X while providing reasons why.
Perhaps a way to have comments of agreement that can also work as signalling your own smarts would be to say that you agree, and that the best part/most persuasive part/most useful part is X while providing reasons why.