Durability?
Meh... It's sort of like the plastic bumper covers.
They are "durable" (like you can beat the snot out of them and they can be popped back out), but not strong.

Those skids might help keep mud/crud from blasting upward as violently, but that's about it.
Why does Toyota slap these on their beast vehicle?
-Because most LC owners never hit a rock.
Ever.
For the rest of us who do hit rocks...we have options.
I have ARB skids on for now.
-My top $ priority right now is collecting pennies for gears/lockers.
But after that...my next largish expenditure will involve trading my very decent ARBs for BudBuilt's superior alternative.