The new PTR patch is a huge miss for healer testing and will result in a lot of skewed data because of Testwerk. There needs to be another test raid (easily accessible and repeatable) with a different damage profile than Testwerk to get proper testing data on priest, druid and shaman.
At the moment Testwerk is probably the optimal raid damage profile for Holy Paladins because of consistent 2 target damage. This makes Flash of Light spamming with beacon look like a good healer design and further masking the design mistakes of the holy paladin rune design. Mage is also fairly well purposed for that raid, as damage profile is focused and predictable.
Biggest problem is that the current test raid provides absolutely no opportunities to test all the runes and capabilities of priests, druids and shaman. Unpredictable damage, raid wide damage and damage that changes target throughout the fight are non-existent, making most of the aforementioned healer toolkits obsolete in the testing environment, thus skewing the data, but also making feedback very one sided.
If testing is done this poorly, you can only expect poor results. So, I advise you to add another kind of damage profile to PTR, because currently you aren’t getting good data on healers.