I want to re-engrave Rachmaninoff works because the "authentic editions" you speak of read really poorly. In other places we have discussed at length the need to be providing works that are error free and clean/easy to read. Some of these older works (see the award winning Fried Songs by Urs Liska et al) very desperately need to be re-typeset.
Not only that, but the LilyPond community needs large-scale works to be created to improve features, drive requests, and kill bugs.
On so-called "immaculate/perfect editions" : I once spoke by phone to a rather well known publisher in the organ field and was inquiring about the Franck Chorales that they had. They said it was "scholarly urtext" but they did not have previews of what the music looked like. I was concerned for the quality, and whether or not the price was worth it.
I spoke with the owner, who was very quick to say that his editions are always worth the money, because they have superior research in musicology and error detection. He was also quick to point out that this version of the Franck Chorales was "a historic reprint of unprecedented quality, free of error." It was also $50. I said, "why not!?" and so I ordered it. For snorts and giggles I ordered Dover edition of the same for about $12.
The edition that was "scholarly urtext" was a 1st or 2nd edition reprint, and it was AWFUL to read. Filled with noise, oversized binding, it was difficult to use. My Dover edition, however, was very easy to read (also a reprint), but had considerably less noise on the page.
I called the Publisher, outraged, that he would charge $50 for a historic reprint that I could find on IMSLP. He said (and I quote), "We were too afraid to re-typeset an edition that would match this edition with it's error-free output. So we decided to reprint it instead."
I went, page after page, and compared it to the Dover Edition, to see if I really needed it. I was furious; I found hand-written accidentals in the urtext edition, with marks clearly made after the fact of this printing. It had be "edited" to cautionary accidentals and various other devices that were not there originally, nor needed. Other than that, my Dover edition also was error free (despite it didn't have some of the cautionary accidentals).
John, I think it is important to consider that editions, no matter how perfect they are in terms of their content, sometimes need a makeover. It is so important that, even if we can make mistakes, we should strive for more perfect editions that appeal to the eyes, the hands, and to the nose. Though we may make errors, somehow it was possible for an engraver to overcome errors in their edition. I believe this can be achieved with Rachmaninoff.
Composer and Transcriber
Teacher and Performer