Do bear in mind that although your essence gets harder to drain the less you have, if a creature does it to you successfully, you die if you have less than 1 whole point to give.
To suffer essence drain, you need to be basically helpless - a vampire that has a potentially dangerous enemy at its mercy isn't likely to just maim him and then let him go. It will feed as fully as it can, then dispatch the character if the essence drain didn't do the job. And honestly, I would rather have my character just die, rather than be permanently damaged, or, even worse, changed into one of the damn things, and be expected to pay Karma to buy the "quality".