Jan 11th 2010 3:56AM You've got to be kidding me.
The IED and it's BC predecessor has long been the lynchpin on raid healers. I don't know how scientific your testing was or what your sample size of data was but feel free to hit up the people over at Elitist Jerks and I'm more than certain they'll tell you it procs more than a "couple times every 3-4 minutes."
Better yet, actually USE the metagem other than spamming heals in Dalaran for an entire raid, then look under "Mana Gained" on your Recount. The restore on this meta is a -huge- amount of mana, even after the suspected stealth nerf to it recently.
21 Crit Rating and 25 SP are negligible throughput boosts from the other options presented, and the 2% Int and 2% mana is ALSO pointless if "mana isn't an issue."