Here is the 'blog' entry for 04/08/08 by 'ariyavansa', the bhikkhu who runs the site:
"... The Discourse of the Great Forty, which is #117 of the collection. This was a difficult discourse to come back to after our break because there some statements in it that are not consistent with the other discourses of the Majjhima Nikáya. It seems quite likely that some sentences were added in at some later point reflecting the thinking of later compilers of the Pali Cannon and of the Abhidhamma. These additions imply a different layout of the path which includes a Supramundane Path along with what would be considered the normal Eight-Fold Path. Whether we consider the Supramundane Path an actual teaching of the Buddha or not should not stop us from looking carefully at this discourse, as it adds an extra dimension to the Noble Eight-Fold Path. For our study of this discourse, I have added to my usual source of the Majjhima Nikáya in the Pali Cannon, the Madhyáma Ágama of the Chinese Buddhist Scriptures to get a clearer understanding of this discourse. So, we have two study pages for your consideration – the First Version of the Mahácattárisaka Sutta is from the Chinese text and reflects what might be called a more traditional view of the Path while still introducing the additional qualities of the Path. The Second Version of the Mahácattárisaka Sutta is from the Pali text and includes not only the additional two qualities, but also speaks of the Supramundane Path which, as I said, seems to be a later development influenced by the Abhidhamma. Otherwise, the two versions are practically identical."
Some info about ariyavansa bhikkhu: http://ariyavansa.org/ariyavansa-bhikkhu/
Best wishes, Vincent.