Energy drain gives them -1 to everything and -5 HP. You don't care if it kills them. It's a stacking debuff and extra damage in one.
When did fast healing become +0 LA? Last I checked, the feral template was one of the few +1 LA templates that's actually worth it, mainly because the fast healing is such a big advantage. Auto-refilling your health between combats is a big deal and would never be +0. Also, losing 12 HP because of a lower Con score is a nightmare, but regaining 15 HP over the course of a combat is useless?
You've also quietly glossed over mind-affecting immunity, permanent death ward, and auto-passing all Fortitude saves.