As an addendum to what Odene said, it is already tricky to say you can judge DPS by DPS meters. Fight-specifics, spec-specifics, gear-level of the raid, raid-composition... these all have a larger impact than the actual spec's power or lack of power in most cases. And let's not even start on player skill yet.
And healing is reactive. Damage not dealt cannot be healed, only overhealed (time which could have been used refreshing the judgement or depending on fight actually running in and melee with SoW for a Holy Pally, for me as a Shammy I nuke ^_^).
As such, much more so than for DPS, Healing Meters don't represent the "worth" of a healer to the raid. Only the amount of healing he/she did, which is not their worth to the raid, their ability to keep people alive is. And then add that healing is a team sport, you don't want the healers to contest with each other too much ,that leads to excessive overhealing.
-- (The Death of Rats, Terry Pratchett, Soul Music)