Cortot editions

Has anyone used the Cortot editions for the Chopin Etudes or any other works? Anyone used his Rational Principles technique book? Comments please!

Personally, I like to derive my own exercises from the music when faced with technical difficulties. However, I do enjoy reading his (somewhat florid) musical commentary, particularly in the preludes and the ballades where he provides programmes (from Mickiewicz’s poems) which can help interpretation.