Here's a link to my guild's Feng kill this week, on which I did 80million healing (21k HPS) as a tank.
http://worldoflogs.com/reports/rt-pm...50/details/42/
Battle Insight did 11.7 million healing over the course of the 8-minute fight, for 14.6% of my healing. That's 11.7 million healing I did to the raid by just having a glyph and doing my rotation.
Bottom line: this glyph is amazing and I can't think of any other Major I'd rather run.