You can be gentle about DH7 by attributing the improved argument to someone with high status. This is my typical strategy and seems to work well. It's a double whammy because you're implicitly associating them with someone of high status e.g. "it's funny you say that, it's very similar to an argument by <famous person>". I'm NOT saying that you actually have to know a bunch of famous arguments offhand, the better argument can be attributed fallaciously to anyone who has spoken on a topic and can have little to do with the person's original argument. Few notice and you have the out of being mistaken even if they do.