The little thing that you guys are talking about, I think, only happens when the page hasn't 100% loaded and you hit back. If you wait a few seconds till the page is fully loaded and then hit back it shouldn't ask you if you want to leave. I noticed it happening with me, but only when I was too quick on the trigger with the "back" button. It's a fantastic feature anyway, as is the auto-save feature. It's saved me a good few times.
As for the little quirk that I'm noticing, it isn't really a problem. It doesn't put me out or anything I was just curious if it was a new feature to help bring the bandwidth down with all the "back" clicking and going in and out the same threads. By not refreshing after only a few seconds between links I bet it would fairly add up over time.
Anyway, I thought I would try to explain better what I've been noticing so I've got an example of where it just happened....
In Dunk's thread here Dunk posted at 16.00. When I clicked "Subscriptions" this came up letting me know he had posted, as it always does, so I clicked on it to read the update. I then decided to reply.... which I did. Once I was finished and my comment was posted I again hit "Subscriptions" to see any recent updates (recent being in the last 10 seconds since I checked last lol). Now obviously the latest post in that thread would be mine at 16.03 but according to my Subscriptions it's still Dunk at 16.00. If I then click the link again to go into the thread, the thread shows that the last person to comment is Dunk. My comment isn't there. If I hit F5 to refresh the page it brings in my comment and any other fresh comments. The same happens with subscriptions, if I hit F5 on it it updates to show all the new replies. Without hitting refresh the Subscriptions won't update automatically for an undisclosed amount of time (I haven't checked how long it takes to update, I generally just hit F5 for updates).
Hope that makes some sense lol.