Not exactly sure how you're deriving 18%.
It's my understanding a 55% reduction to healing is 55% reduction to healing. Resilience is a reduction to damage. They are only equivalent if damage and healing scale equally, which they don't.
What I'm seeing on my h.pal is what healed for 700 last patch now heals for 300, excluding additional healing debuffs. By comparison, I'm seeing serpent sting ticking for 100, explosive shot hitting for 250/tick, shield slam and slam at 600 (all noncrit) , aimed shot and ambush at 1100 all from non fully boaed 20's. (ot footnote: serpent sting ticks for more than all lock dots combined with similar gear).
Essentially you need 2 healers to do the work of one last patch all things being equal. Unfortunately, things are not equal as hunters and rogues make up about 70% of all matches I've seen recently and 24's seem to be more and more common. The net effect is that healers in a pug need to be better than they used to in order to add more value than just another hunter.