Yes, heavily, and in contact with manufacturers, but results are essentially identical. DVD media is a mature format, with just a few manufacturers, and nothing has changed in terms of materials and processes.
- Verbatim/Mitsubishi (made by CMC) is still the best media.
- Taiyo Yuden (made by CMC) is still tied for best.
- CMC's own media is still bottom end.
- Ritek is holding steady at 2nd place, though not by much, and their media is more readily available. If anything changes, it will be that Ritek is suddenly the best media available. Testing is ongoing, and that may happen eventually.
Amazon is still be the best place to get these discs.
(Though now, due to the pandemic, tech-only stores may be your best bet. For example,
Newegg or
CheckOutStore, maybe MediaSupply. Sadly, places like SupermediaStore and Meritline are no longer in business.)