Thanks to ⌗breydon_music for signalling the release of this new set from Pentatone - it has indeed been released generally. Clips @ Presto sound promising.

Pity the new Bychkov "Ma Vlast" recording has been released as a RBCD only. I have no idea what Pentatone are thinking but surely there will be more customers for Smetana's tone poems than for the new Schumann set so why not SACD?

One should remain satisfied for small mercies, I guess.

I share your frustration with the Bychkov / Czech PO issues. The answer, sadly, to your point about Pentatone's priorities is that they have none - everything they do themselves is PCM and RBCD. The few remaining SACD's are recorded by the San Francisco Classical Recording Company - the new home of all the "real" Polyhymnia guys. Presumably they reached a deal with the young bucks before they left that their future product would be released through Pentatone and remain on SACD. As you say, beggars can't be choosers, though the epithet seems a little ungracious when the standard of their offerings is generally so high in every respect. By the way, there is a Haydn Schopfung on its way from Jablonski and "his" orchestra in a couple of months - and yes it's a SACD set!

NativeDSD web-store does offer DSD files (up to 512) of a lot of these PentaTone releases, "upconverted" from PCM. I don't know what process they use for that though. Does anyone know what they do?

Check out this description from NativeDSD of how and why they offer multiple formats and bitrates.
https://www.nativedsd.com/product-tag/higher-rate-program/

The higher rates program at NativeDSD is all about getting the DSD modulation noise away from the audio band. Each doubling of the DSD rate moves the modulation noise up one octave. Tom Caulfield explains it pretty well in his blog and writing.
The net effect of this is really rather subtle at best since the DSD modulation noise for DSD64 is just above the audio band and inaudible as is. I recently bought a DSD256 download of a DSD64 recording. I really could tell no difference at all. But perhaps the DSD256 files were a little quieter, maybe. I don't think I would be able to tell the difference in a blind test. However, FWIW, the DSD256 files are 4 times larger than the DSD64 files.

While Pentatone often records in DXD, this release was recorded in DSD64, according to NativeDSD.

This Schumann is my new favourite.