I believe the updated R500-700 drivers may have also had something do with your exhibit at Amiga34 more than satisfying the needs of a current X5000 or Sam 460 user. They just happen to be cards which can also be used these machines in AmigaOS with limited functionality in the same way that these offer the same limited functionality in MorphOS. Most of us were curious to see what type of card was running on the Ryzen set up and saw it was a 4650 card right?
Support for more modern PCI-E cards will be required as part of your long term transition to AMD64 boards, so you will need to test these out regardless across all Radeon series levels. I'm certainly of the opinion that its better to have a range of eager guinea pigs than none at all. Personally for what most X5000 users I've spoken to and what they have told me, 2D support will be sufficient in MorphOS, if they wanted 3D gaming, they have the option of making full time use of a 1650-1950 range of cards in MorphOS full time which I have shown, but which none of them have done, otherwise they can stick with what they have in AmigaOS even with a more dated browsing experience. But contrary to perception, many do want to join in the fun, especially as a 2nd graphics card isn't supported in MorphOS on the X5000. My blog stats certainly can back this up