PLEASE, let us keep this initial draft confidential: I may change my opinions once I have been working more deeply on this matter. Thank you!
I have often been told that Heugel (Alan Curtis ed.) 1970 (let me abbr. HAC) had been vastly surpassed by L’Oiseau-Lyre (Davitt Moroney ed.) 1985 (let me abbr. ODM).
Obviously the musical texts appear to be slightly different, as they are based on a comparison of the MSs Bauyn, Parville and a other minor sources.
Back in 1986, in the EARLY MUSIC magazine, May 1986 pp. 284ff., Richard Langham Smith wrote a review of ODM and compared it with HAC. He observed that ODM is a reprint, with corrections by Moroney, from the plates of an original edition from the 1930s. He also devoted a page to the question of the performance and notation of the Préludes. Finally, he observed that HAC tends to favour Parville and groups pieces in suites, while ODM tends to favour Bauyn and groups the pieces by tonality (as per the sources). However, Smith makes is no attempt to compare the musical qualities of both scores.
Which is what I have started today, mainly trying to find in ODM fixes to some readings in HAC which I find suspicious.
So I first spent the afternoon writing in HAC’s index (TABLE DES MATIERES) the page number equivalent in ODM. When this chore was over, I realised that entire pieces in either edition are missing in the other one.
Most notably, about two dozen pieces in ODM are missing in HAC (many pieces in Bauyn are of dubious attribution). So far so good, and this fact has been often commented upon.
Unfortunately, these missing pieces include at least one great masterpiece: a Chaconne in C major (w/4 Couplets), featured in a private recording by Scott Ross (Paris 1971) of which I have a copy.
Vice versa, a few pieces in HAC are missing in ODM. Among these, a handful on pages 179ff. The last page of the PDF carries the number 177. But my PDF may be a downloaded copy, not necessarily identical to the one that was on sale until a few years ago.
So far I have just carried out a very a cursory comparison, expecting to find ODM superior to HAC, according to prevalent opinion in harpsichord discussion forums (where Moroney was a member but Curtis was not) for decades.
Surprisingly, at first sight I find quite a few errors in the sources which are fixed (mostly as a suggestion between brackets) in HAC, but not in ODM, who obviously prefers to leave the originals untouched. Most of these are obvious trills and mordents. I just compared a piece which is arguably the best Sarabande by L. Couperin, in b minor, p. 35 in HAC, p. 169 in ODM: in the first section of the piece, ODM carries no trills, while HAC carries four (!), one supposedly original from a source, the other 3 suggested. When a source carries a cadential trill with a written-out termination but not a trill sign, all modern editors suggest a trill within parentheses for the benefit of the non-specialist player/student. Unfortunately, ODM begs to disagree and does not add suggested trills.
Even worse is when what is missing is an accidental: upon sight-reading one easily fails to realise until the wrong note has been played.
I intend to write more once I have made a thorough comparison of a few pieces in both editions.