I really like this solution and agree "bookmarks" are a lot better than outbox, but it is hard to guard against races where the reader increments the bookmark

I really like this solution and agree "bookmarks" are a lot better than outbox, but it is hard to guard against races where the reader increments the bookmark before an active transaction commits an ID at an earlier position; if transaction commits in a different order than IDs are allocated. Perhaps this is what you mean with "out of order increment"... but what are the "many" solutions to this? I struggle for a long time to find a good way of doing this in Microsoft SQL and still not perfectly happy about the solution we found.