I mentioned my alternative (literati.sty) elsethread --- it's rough around the edges, and a bit awkward to set up for a new project or to add support for a file (two files need to edited to keep in synch) and it doesn't automate line numbering fully, but it's the best option thus far for how I work.

All of which shows why there are so many Literate Programming solutions/implementations --- it's a fairly simple problem (though I'm a lame programmer, so had to get help on tex.stackexchange) and it's easy to roll a solution to scratch a particular itch.