Currently, using the Inbox as a notification centre results in large numbers of page swaps and reloads, as you go from Inbox to post to Inbox to reply form to Inbox etc., etc., etc., with mark-as-read and delete-item as separate actions across separate pages.

I hadn't thought about this until you mentioned it but maybe this is indeed why my Dreamwidth inbox is stuffed to overflowing and I don't interact with it much!