I haven't heard Guillou's recording in a few years, but I when I first heard the Latry recording, I nearly fell to my knees with this track. I think the most spectacular aspect of the recording (apart from the Notre-Dame organ) is the judicious use of legato, particularly at 3min 30secs.
As much as I love Jean Guillou, I wonder if he has played legato since 1967!!!
P.S Would you be willing to share an mp3 of Guillou's own performance?
Cheers
Theodopolis