Not eager to respond to all your questions, because you don't bother replying to my pm's either, but I'll say this about DPM:
also this might be a dumb question, but is there any possible way to get an 100% accurate descriptor file or is this just one of those things that our drives can't do 1:1?
I think nobody here ever really looked into the ways of preserving the Data Positioning Measurement data, because the format is proprietary/undocumented and the results seem to be different for each drive and even on the same drive if it's dumped multiple times or at different speeds. We could've gone the trurip way on this and preserve a single dump, but redump is about verifiable results. This is also why we're not hosting full subchannels: It's almost impossible to obtain 100% clean unaltered subs. Maybe this approach doesn't help preservation in the end, but since it's essentially metadata, it can always be added at a later time once a sensible preservation method is chosen. The SecuROM subchannel data was added 10 years later, but it only took us a couple months to recover more than half of the missing data (although some discs are missing the pregap sector).
It would be interesting to get some more info on exactly how the DPM data is retrieved and stored. If anyone has this info, feel free to let us know. Maybe a better way of preserving this would be to retrieve the accepted range of values from the game binaries in some way that the game checks for (good luck with that).