The thing is, that if you have an infinite healthpool, constant damage intake and no overhealing (theoretical scenario) then 10.5% DR are exactly equal to 11.7% more healing taken. The thing is, if you take a hit for 1000 Damage and you have 10.5% DR, that means you need to get healed for 895 (because 1000 - 1000 * 10.5% = 895).
On the other hand, if you have 11.7% more healing, then you still need to be healed for exactly 895. because 895 * 1.117 = 1000.
1% DR is right about equal to 1% more healing, but the higher you go(5%...10%...50%) the higher the difference gets. Thats why I said Versatility scales way better.
(To the point of 100% DR via versatility, where you do not need to be healed at all, which is unachievable via crit)
And while stacking crit does make it more reliable (not really "reliable" thou
) it also becomes way worse in higher gear levels because like I said, crit scales worse than versatility
Damage wise i am not even that sure crit is that much better. Lets compare 21% versatility rating to 24% crit rating. You have a base crit chance of about 15% + 3% from Gifted student. So the real values to compare are [21% vers + 18% crit] vs [42% crit]
1000 Damage (with vers) become 1000 * 1.21 * 1.18 = 1427,8 Damage
1000 Damage (with crit) become 1000 * 1.42 = 1420 Damage
So even damage wise crit is worse than versatility (given a high value) This should obviously be plotted on a graph because it changes with current crit/vers levels.
On top of that you have to consider, that crit does not affect Special Delivery (Don't know if versatility affects it) and BoK profits even less from crit (since it has 9% more crit built in).
This does seem kinda strange, since crit has the better rating conversion, but the fact that you also have way more base crit negates this completly.