As a long time DP contributor, I'd say the models could not be more different. DP is elaborately and deeply organized around the model of a great many people doing a great many small units of work (stop by once a day and proofread just one page for very specific things). This minimizes the responsibility any one person needs to feel for a book. And like the citizen science projects at zooniverse, individual mistakes are corrected in a multi-pass process where multiple people (5 or 6) see every page.

The new project follows the Github programming model, which means if a person wants to contribute to a book she has to clone the book, make local changes, push, issue a pull request. This is far, far more complex than stopping by pgdp for a ten-minute proofing session. Very few of the drive-by proofers at DP could manage that technically, or would want to be that involved.

Most important it lacks the QC inherent in the DP model of having multiple later reviewers catching earlier errors. Who will do line-by-line vetting of the accuracy of pull requests? Besides the inevitable detail mistakes, there are potential problems similar to those faced by Wikipedia: who will even notice if some local zealot decides to insert editorial comments in, or to bowdlerize the language of, some classic?

It's true that DP's work ends when the book is posted to PG, and that PG has only a feeble update method (email to their errata contact). I could certainly see something like this project as an adjunct to PG, dedicated to continually refreshing the library, but with editorial control over which books go into it.