The link to the implementation is 404 and I can't find it in that directory either. A quick search of LLRB trees suggests that its only advantage is supposedly "easier to implement" but that doesn't appear to be the case in practice. In fact one of the links I found is http://www.read.seas.harvard.edu/~kohler/notes/llrb.html

It almost feels like LLRB trees are a bit of a scam.