I think that is a good idea to keep URLs as text. I use the Tab Session Manager extension which allows me to export saved sessions (title, URL, with a little bit of extra stuff) as text (json actually, a little bit too verbose) and I also use Eagle Filer to save entire web pages, just in case it disappears from the web, which happens quite regularly. What I want is the title of the web page associated with its URL and maybe extra keywords. I don't use classic browser bookmarks much anymore.