I don't know how it works (the more damage the more HP drained, or fixed amount of HP) but if you have Health and Aid Self taking a bit of damage for insane damage is worth it and even if you don't you can get away with it. ET + TF is what makes Energy outdamage every other melee set, so take both 
It is fixed.It is a 11% of your health.
is it worth it? 1 million times YES.
Energy Transfer is the most damaging single target attack in the game, and the hp loss is very barable.
This power is the whole reason for taking energy melee.
I really should do something about this signature.
Hmm... I am getting a very subtle feeling that perhaps it is worth taking!!
Thanks all
One-shotting things can be FUN, kids!
DON'T eat muffins while I'm developing you.
Pants! Turkey Magnates! A man in a box! Rogue AI! Come one, come all, to arc ID 10107 - It's [i]'Not as long as some other arcs'[/i]!
Show me a brute that cant one shot things, and I'll laugh in his face (until he's hit me once then I'm gone)
"Well, they found my diary today.
They were appropriately appalled
at the discovery of the eight victims
They're now putting it all together.
Women wrapped in silk
with one leg missing
Eight legs, one body, silk,
spider, brilliant!"
With ET my tank can one-shot things.
I really should do something about this signature.
PRAF wins the internet.
I'm 1 level away from ET. suffice to say that I will probably cry with excitement when I next ding.
[color=dodgerblue] Very worth it, energy set is the boss taker-outer, build up, bone smasher, ET, TF, n that should sort most things
very worth getting
Just incase you were still unsure.....although somehow I think you already know....Its amaizing, and just magic in PvP as an opening attack, loved making regens jump at the sight of their health in that RV event.
I'm soon to use my freespec on my lvl 33 EM/EA Brute and am wondering whether the Energy Transfer power is worth it. I can see that you sacrifice HP for Damage but how does that work in the combat environment? Is it variable??
Any help would be appreciated.