You have strong normal heals though? I previously mentioned PoH: it has the potential to push 80-100k hps, which is around 33-50%~ better than CH which can generate some 55-70k hps (depending on buffs, ES, RT etc). You have Atonement which is a very strong source of healing. I think Atonement is actually better than the Mistweaver Eminence, Atonement is a 1.5 sec GCD vs a 2 sec GCD (1 for Jab, 1 for TP). I really do think you should wait for some empirical evidence. Guilds will be testing the PTR tonight, and if Discipline Priests are inline with Resto Druids (who I think need more buffs) then I'll agree there's an issue. If however a Disc Priest is tied, or slightly below, a MW then I see no issues with that considering the amount of utility a Disc Priest brings.