Pros and Cons of each Healer Role

[Pells]

Parry is a terrible analogy. [...] Since you know this for sure you can act appropriately. Redirecting your time and resources if the extra mitigation afforded by the crit gives you room to so. If you don't get the crit you can act like you always have. Since the information on the shield size comes after a cast and as part of your normal healing activity, the crit is always actionable.

This makes a crit adlo more comparable to Bloodletter or Shield Swipe. Neither of which I ever hear complaints about being unreliable.