The Benediction bit is what really pushed me away from WHM towards SCH. As Kondor said, SCH gets a max of 75% HP from 3 Lustrates a minute where you get a Benediction cooldown that heals 100% every 5 minutes. Not really sure that the ability to burst that much HP in one go is preferable to having 3 short bursts at 25%, but maybe I just haven't seen a situation where I couldn't deal with it using Lustrate.
Then again, this is kinda like the argument that WAR had nothing to compete with PLD's Hallowed Ground, so they got Holmgang, so make of it what you will I suppose.