Knowing that I'll just end up going back to where I started, I just middle-click to open that first link in a new tab. That's not to suggest that some people wouldn't find it useful to be able to navigate back to the most recent change in base level domain. (Or, perhaps, by configuration, to the most recent change in full domain name.)
To clarify, based on the comments below, I posted this answer which doesn't directly answer @Jack's question because in my experience there are lots of people who don't know how easy it is to open links in a new tab (for example, recent convertees from IE6). That, for me at least, precludes the need for this extension. I try to follow the mantra of less is more, so when I can use existing functionality to solve my problem I prefer that over adding more extensions to Firefox.