The truth is, a frozen/thawed rodent never bit a snake ever.
That said, I feed live, supervised. Never really had any issues. The few times I've had a snake get bitten, it's not even been a wound. I'm pretty sure a large rat could do damage though. I just hate the thawing out of 40+ rodents for the snakes to suddenly decide no one is hungry. Then I have 40 thawed rodents.