Backstabs are crits, but they cannot also crit.
For example, the ability Vault says it always triggers a Backstab.
I use Vault and do 243 damage. It says "Backstab Critical" and "Critical Hit" when I use the ability. This is with me having 1% crit chance.
I then reload and use Rage, then Vault. The attack hits for 245 damage. It says "Backstab Critical" and "Critical Hit".
The damage is essentially the same. There is no bonus for having 100% crit as opposed to 0% crit on a Backstab hit.
Do you have an example indicating otherwise?
