What I did:
I got on the PTR. Bought 5pc T16 plus trinkets and lots of gems/enchants. I ran multiple setups including forging out of spirit to full spirit and also haste and mastery variations. I then played each of the tier 45 talents to OOM as well as using the tool tips to see what the healing should be. I also used the last tier’s tier to estimate over healing numbers on direct heals, hots, beacon of light, illuminated healing to get a better idea of what the rotations will look like on live. To see about what I did here is one of my sheets for a full haste build forging out of spirit using Amplification trinket:
Number wise you can see that the difference between Mastery and Haste is not amounting to very much. Each are nearly identical in output. There is a significant mana usage difference however on most setups. So as of now I will be sticking with Mastery > Haste but stat weight wise they are on par.
Spirit will depend on your setup. If you are running Selfless Healer you can ditch all your spirit (9k) and have great output and without all raid buffs go OOM in 4 minutes. This is about how you will fair with a full Spirit build doing SS/EF with Holy Radiance as a HP generator. If you stick with full spirit (17k) on Selfless Healer you cant go OOM if you do the rotation. At about 13k you can go 10 minutes before you are OOM. NOTE: Legendary Meta on PTR is not working so these numbers will be off to live. However, I am betting with raid buffs and the meta you can do less than 11k spirit and be able to heal full on without fear of going OOM. At heroic item levels we might be able to forge out of spirit and have enough residual spirit to never OOM. The bonus you get in Mastery and Haste doing this is substantial.
I also want to state EF and SS are not dead. The output on them is still just as good as SH except for the goofy no spirit versions. My numbers for EF account for not applying IM on the HoT and accounting for over healing and it is showing to be just as strong as rolling 3 Sacred shields or a sustainable Selfless Healer.
EF was a big nerf to our play style so I am still worried that the other options are showing to be fairly equal. We did get buffs to the baseline healing on EF/LoD/WoG as well as to Kings and haste reducing our holy shock cd but I am not sure it will be enough to compete with the likes of Disc. In the end it really isn’t about us, it is just how we compare to OP/Useful mechanics like Atonement and Spirit Shell.
Last thing I want to say after spending quite a bit of time rolling through the different rotations Selfless Healer is kinda fun but it feels more like a dps than healing, but without the usefulness of the damage. When you go back to a Mastery/Spirit Build doing SS or EF it feels painfully slow. Regardless of what we end up doing healing has turned into a game of sustaining a constant healing output and less about triage and decision making.