What I will say is just my opinion, please correct me if I am wrong somewhere.

Yes, the downloadable portion of Audiophile (30GB) based on Flac files, not Wavs. That's just the 2025 portion. By installing it over your 2024 Audiophile, it will make it whole. It should work seamlessly, however, You will have a mixture or Flac and Wav files.

The upgrade version that ships on 1Tb SSD hard drive, has complete 2025 Audiophile version in Flac (not just 2025 content). So...for $25 extra PGM charges for HD, it's no brainer to get it during the special they are running now. My plan is to do a complete clean FLAC install of Audiophile on internal drive.
2025 Flac Audiophile version is only 1TB, compared to 2TB from 2024. So, for one, it will save 1TB of internal storage. Think about this if you are running it that way. In the future, I will only be getting downloadable "update" portion instead of the hard drive.

Don't quote me on it, but I believe, when you purchase a HD, you can still download upgrade and explore it while until your HD arrives.

P.S. I am sure that at some point they will offer full Audiophile download. First step is made and to me it's a big deal.