Rated 3 out of 5 stars

This is in response to your comment about not wanting to create an "alternate interaction" (in response to my request for right mouse support)

Today, I needed to update the bookmark for http://sundaystreetssf.com/ with http://www.sundaystreetssf.com/ (FWIW, my bookmark is titled "Sunday Streets San Francisco"). Replace Bookmark reported "No related bookmarks found." The bookmark was there, of course! THIS is why I suggested adding the right mouse functionality from Update Bookmark. Over half the time that I try to use Replace Bookmark, I receive a "No related bookmarks found" and am forced to do a manual edit. It is no different than not having the extension at all. With the proposed "alternate interaction", your addon would be functional 100% of the time. Mo' betta IMO! :-)

This review is for a previous version of the add-on (1.3.1.1-signed). 

It seems that "over half the time" you're trying to use this addon for purposes I didn't plan for (see description).
At the moment, like the description says, it only shows bookmarks from the same domain (including "www" part). But I could make it recognize subdomains.
Please post an issue here: https://github.com/dgutov/bmreplace/issues

Rated 4 out of 5 stars

Nice extension. I would like a bookmark context menu item, so that if I "right mouse" on a bookmark, one of the options is "Replace Bookmark with current URL" (which would substitute the current URL for the URL in the bookmark). Compare "Update Bookmark" (which hasn't been updated since 2008).

This review is for a previous version of the add-on (1.0.1-signed). 

I don't really want to create an alternative way of interaction.
If what you're trying to do is avoid overwriting custom bookmark titles, you might want to try the new version.