That way posts being composed would be preserved as now and that is good.
Those six pages are the key ones for refresh because we always refresh when going back to them. Putting a tag on just those six should be easy and have no adverse affects. Or just do not put it on the Post a reply and Edit pages, since those are easily identifiable, and use it on most or all other pages. (Wouldn't need it on Journal, Profile, or info pages.) If a meta-tag to prevent caching can be put on one or six pages it could be put on most. If it is on most pages, like thread and post reading pages, that would help. Currently, now, if I post on a thread, I see it on the page that comes up, but then when I go back through the Post Reply page and back to the thread page where I decided to post from my post is not there and I have to F5.
Also a meta-tag on most pages would mean that DU tabs would be dependable when yellow or blue instead of being flaky depending on F5.
I hadn't looked for an extension, good idea, so I just took a quick look. It seems there are some for tabs but page refresh seems to be broad spectrum.
I don't know if you really want people to put refreshers on DU pages and browser tabs every ten seconds. People would leave it running all the time which is a useless load on the server. People who use the back button on the site might go back to pages say 200 times a day and that's all the refreshes they need. Auto page refresh every 10 seconds would be a 2,880 times in an 8 hour day on multiple pages. It also would not be effective. When I go back, I have to (want to) hit F5 within less than a second. The temptation would be then to put refresh on those six or more pages or site-wide every second to avoid any delay. Not good.
Another problem with auto-refresh extensions means that refreshes would disturb reading. If I'm reading a thread and in the middle of consuming a good post with a few paragraphs and the page updated with a new post higher up, I get interrupted and have to find my place, and it might necessitate using mouse or buttons. With meta-tags it only refreshes when we want it, when we use the back key / button.
I think selective use of meta-tags would maintain or increase engagement.
Whatever you decide, always a great site.