I get what you're saying and yea I pug, but its easy for me to glance at hp bars to see who needs heals. Noticing tiny confession icons amidst the other buff icons less so.
The proc rate is indeed 100%... unless someone gets topped off by your co-healer... or everyone gets topped off by your co-healer. As I mentioned above, I mainly pug so coordinating with my co-healer isn't a realistic option.
As I said PI is better than it was but it's really not a great level 70 ability (unless perhaps if you're in a static doing savage content and can coordinate with your co-healer effectively). For all intents and purposes (for me at least) it's just a 150 potency aoe heal every 60 seconds. Hardly anything to get excited about. It just feels like a very uninspiring button to hit.
But I'll happily take the PI we have now over what we had at launch.