Thank you very much ozgeorge for that clarification! You the Bomb!
BTW, why would a monk from the Holy Mountain be reading Latin Spiritual Treatises? Don't we have Spiritual Treatises of our own that are much better? Just asking...
Interestingly enough I just got this book today. Still in the introductory of the book, but to answer your first question. it seems to me that St. Nicodemos lived in a time when the Greek Orthodox Church were being oppressed to a certain degree by Turkish rule. Thus the Greeks were driven abroad to seek their Higher Education and Theological learning which was difficult in their country. Priest and Theologians went mainly to Italy thus they came under the infleunces of the Roman Cahtolics, that is probably where St. Nicodemos came across the book.
The fact that two great Saints, St. Nicodemos and St. Theophan, who were both well versed in the Orthodox tradition, saw value in the book to the extent that they wanted the Orthodox family to read it shows, it has something in it, that others writings may not touch upon this issue of "Purifying the heart" in such a manner.
It is not an issue of better, it is on this particular issue, the Latin Saint made some good points. In the Philokalia, there is a text in it, that the translators felt was not originally Orthodox Christian but from Greek Philosophy.
The beauty that it shows, is that Orthodox Christians, or at least some of them are willing to recongize the truth regardless of where it comes from, which shows that Orthodox Christians are not closed minded. Another beauty that is shows, is that eventhough the Orthodox and the Catholics disagree on the some of the outward aspects of the religion, we seem to be united on spiritual matters. There is hope that one day we will be united with our Roman Catholic brothers and sisters.