According to wowanalyzer Doorway is up to 5.6% total healing. The rest (8.25-5.6=2.65%) is Chi-Ji from the talent.
Sure you can't bring over 2mHPS over 7 minutes without infinite mana. What I found interesting here is that T21 bring 10% additional healing without optimization of gameplay. It seems also that Doorway needs lucky proc and almost EF casts on CD to be good.
My point is that RJW is presented as the talent to go whereas it should be a situational talent especially with a T21 that can bring a tons of additional healing in a very mana efficient way (Effuse+SG).
So my question is what legendaries should be considered if you do not used Spirit of the Crane and RJW but Mist wrap and Chi-Ji? I suppose that it still should be Velen and Prydaz (or Petrichor if you can get an additional Revival).
I like to use the chest on Varimathras. I spot heal with effuse and pre-cast SG on tank when debuff goes off (little to ne SG overhealing), it seems very strong here.
I also have some interrogation about mana return trinkets (Darkmoon or Amalgam for example). If you use the additional mana to Effuse and SG it should increase the mp5 weight but to what point exactly?