Evan, if you can accept DVD/Blu-Ray versions, Pichon (2020) uses the 1757 version of Hippolyte. There is also a Rattle performance from Berlin (2018), which I have neither seen nor heard; it may use a mixed version.

As for Castor, I own the Christie recording and have streamed excerpts of the recent Vashemyi; I have never heard the Harnoncourt recording. For what it is worth, I find Christie's conducting superior to Vashegyi's, who seems to be a man in a hurry. Christie's more measured tempi add clarity and pathos, at least for my taste. Nor do I find that Vashegyi compensates by offering more excitement. To my ears, Christie's soloists and choir also have the edge over Vashegyi's. Neither Castor is ideal, but I prefer Crook for Christie to Van Mechelen for Vashegyi. Gens' Phébé for Vashegyi is bettered by her younger self for Christie, and Christie's Télaïre sounds more idiomatic that Vashegyi's. The minor roles are also more consistently cast in the earlier recording.

Vashegyi attempts to follow the conventions of Rameau's day closely and uses the most recent edition. I have no doubt that research on these matters has made progress since Christie's recording in the early 1990s; Vashegyi's choices may be "more authentic" (I am not a musicologist specializing in Baroque opera and have no way of knowing), but I still prefer the earlier recording.