So I went out and did some extreme slug-battling with and without these new corruptions slotted, 10 fights per test to get an average.
Without any slotted 23.56% of my heals were crits.
With 3 slotted, 42.14% of my heals were crits.
(each fight I'd auto-attack, then pop Fungal Spores and Fertile Slime, wait for them to fully tick over then end the fight)
Not too shabby I'd say, my testing probably wasn't extensive enough but how do you guys see these new corruptions? I'm looking more from the healing-side really, since as a defiler I have all the DPS of a paper-bag.