Auto-tune, how much?

Listening to the radio en 2012 I am noticing tendencies in the commercial vocalists world. Great and popular singers are splitting teams between the auto-tuned and the raw natural vocal tracks, of course keeping in mind the style of music, R&B uses it more, Heavy Metal not so much.

The most hardcore singers we hear in the radio are all awesome vocal performers, with great vocal training and stage presence and according to their musical inclination they and their producers decide to sound in very particular ways, one of them is the auto tune.

Any vocal coach would advise against auto-tune, however, I think it could help you get out there, but there's a particular formula to use it: not too little that it becomes only help but enough so you can hear it, and not too much that discredits you as a vocalist.
Singing lessons are the key to render a decent vocal track. Talk to your producer and your voice trainer, they can help you figure out if, and the amount of auto-tune you should use in your mix.'
Remember, 3 or 4 sets of ears listen more than one.