Looking at the new ranks of Healing Wave (data stolen from Wowhead), they're... special. The other big heals are included for comparison.
Priests' Greater Heal rank 7, trained at level 68, heals for an average of 2590 at the cost of 825 mana, resulting in a HpM of 3,14.
Priests' Greater Heal rank 9, trained at level 78, heals for an average of 4270 at the cost of 1290 mana, resulting in a HpM of 3,31. The mana cost is increased by 65%, and the end result is a slight increase in efficiency.
Druids' Healing Touch rank 13, trained at level 69, heals for an average of 2952 at the cost of 935 mana, resulting in a HpM of 3,16.
Druids' Healing Touch rank 15, trained at level 79, heals for an average of 4768 at the cost of 1400 mana, resulting in a HpM of 3,41. The mana cost is increased by 50%, and the end result is a slight increase in efficiency.
Shamans' Healing Wave rank 12, trained at level 70, heals for an average of 2285 at the cost of 720 mana, resulting in a HpM of 3,17.
Shamans' Healing Wave rank 14, trained at level 80, heals for an average of 3250 at the cost of 1600 mana, resulting in a HpM of 2,03. The mana cost is increased by 122%, resulting in effiency that's lower than what LHW has currently.
Similarly, Lesser Healing Wave goes from 2,53 HpM to 1,78 HpM. Earth Shield goes from 3,6 HpM to 1,98 HpM. The same goes for ranks learned between 71 and 79.
My question now is, well, lolwut?