yea, i know about loken. I wiped alot with my DK on that guy, 3-5 wipes in HoL wasn't that bad back in those days. But as Disc priest atleast i've never found stuff "hard" or whacky in 5 mans. Yes things die sometimes (over confident tanks for example, that try to pull half an instance. Or PoS, the tunnel, a new tank with just full epic will near sure die without a heal while running) but i guess being a shielding bastard made my life alot easier. having a 6k pre-heal on everyone, that is instant cast + Prayer of mending, that, with the small amount of ppl in 5 mans, heals the right ppl very often makes stuff trivial, even when not outgearing.
the only thing i found really hard in 5 mans was ToC5, rogue on the first encounter made healing in blues impossible as i can't dispell it, the fearing second boss nearly oneshotted me with every smite she did and i couldn't keep up with the dark knight with his 6k-ticking diseases and AoE damage.
Anyway, i don't mind all healing classes getting new tools. Blizzard tries very hard to make every class unique and i love that. Try comparing the AoE heals of a druid, priest, paladin and a shaman...
Druid: HoT's on the raid
Priest: You cast a heal on a target that heal the nearby groupmembers for the same amount
Paladin: Radiation heals players around you
Shaman: Passive AoE + chain heal, that heals 2 (right?) low health targets after healing your target
i love the diversity that achieve the same goal, healing your group / raid with one spell instead having to cast multiple single target heals