Thanks for your comments.
Glad to know that already a project is ongoing to fix these problems. Would be more than happy to help you guys if you need anything related to testing or any other suggestions.
My another request in this front would be ability to do on demand search from MusicBrainz from the PlayList UI - the same way one can do it for Discogs. In general, my suggestions would be to have a long term strategy where user can himself/herself pick and choose the meta data from various online databases. Then the same would be downloaded in the SD card. That way from PS Audi’s side you don’t need to cache/store any data for long term - the Playlist page just enables the user to do the search and selection (or enter/edit meta data wherever needed).
Regarding SACD my experiennce is so far limited to only Hybrid SACD. Ehat I found that in case of Hybrid SACD, DMP computes the disc id using TOC of the redbook layer. Since the same disc id is also used in MusicBrainz and freeDB it should not be difficult to match the same. Example is the Hybrid CD of Captain fantastic and the Brown Dirt Cowboy (barcode - 60249824120).
For pure SACD (like SHM-SACD), I don’t think it would be possible for end users to get the TOC of the SACD as it is only possible to do the same through Play Station, legally. No regular disc drive can get the same. So not sure how one can enter the disc id for the same in MusicBrainz or any other software as they get the discid from the actual disc. So in this case user has to create the meta data manually. Probably P S Audio can write a program using MusicBrinz APIs to update the disc id (I am assuming DMP can read the disc id like Play Station does for SHM-SACD) and metadata of SHM-SACDs to MusicBrainz after the user has entered teh data manually (and gives permission to share it in a public site).