Is it the moment in each person's life when they made a conscious or unconscious choice that would effect or direct (possibly) the rest of his or her life? And is 'Jacob's death' the moment when each one had an epiphany ... an opportunity to rethink that choice.. "to go back from where you came, and see if for the first time"?

Jacob's touch:
- for Sayid, when he decided that Nadia was his whole life and how would he ever live without her (she didn't really need to die for him to decide this.. only to experience the choice of her importance to him)
-for James, when he decided that he would blame someone (rightfully or in a child's imagination) for his parents death.
-for Kate when she realized that she got away with a crime (petty or not)
-for Jack after he had just been humiliated by his father once again
-for Hurley when he panicked at his sudden wealth and started to hallucinate
-for Claire when giving up her baby hit home
-for Locke when he smashed his spine.
-for Jin when he chose to marry and lie that his father was dead.

Is Jacob real, or a metaphor?

I don't agree with your theory. I don't think were are any epiphanies or un/conscious decisions at the moment of Jacob's death.

If we're to believe Richard, and "Jacob gave him a gift," then those Jacob touches can't die, at least not by their own hand. Richard seems pretty certain of this, like he's tried it before. Hence, making Jack light the fuse.

Cases in point:

Jacob touched John after he fell from the window, John didn't die. John was killed by Ben, but when John tried to hang himself, would he have succeeded? Probably not.

Jacob touched Sayid and even though he was shot by Roger and drowned in the temple pool...he came back to life.

You mentioned Claire...when was she touched by Jacob?

And don't forget Michael, we don't know if he was touched by Jacob, but he did try to kill himself and "the island wasn't done with him" so the gun just went click, click, click.

Does the island = Jacob? Literally? Not metaphorically.

I don't agree with your theory. I don't think were are any epiphanies or un/conscious decisions at the moment of Jacob's death.

If we're to believe Richard, and "Jacob gave him a gift," then those Jacob touches can't die, at least not by their own hand. Richard seems pretty certain of this, like he's tried it before. Hence, making Jack light the fuse.

Cases in point:

Jacob touched John after he fell from the window, John didn't die. John was killed by Ben, but when John tried to hang himself, would he have succeeded? Probably not.

Jacob touched Sayid and even though he was shot by Roger and drowned in the temple pool...he came back to life.

You mentioned Claire...when was she touched by Jacob?

And don't forget Michael, we don't know if he was touched by Jacob, but he did try to kill himself and "the island wasn't done with him" so the gun just went click, click, click.

Does the island = Jacob? Literally? Not metaphorically.
I don't quite understand your response.. but by 'metaphorically', I mean that really Jacob doesn't actually exist. All these people had specific beliefs or hang-ups that they were living with. What started them on a life of being controlled by these beliefs or hang-ups.. the spark, if you like, was what I call Jacob's touch.

It was emotional.. an emotional decision, for right or wrong. Looking at it that way, death is not a physical death, but an release of that spark that got them on the path they were following. And you can't kill that with suicide. You can only kill it by understanding it.

How I see it, is that their non-island lives, and the sideways lives are real. The island, and Jacob, etc, are spiritual experiences that correct (or don't) the paths that had them in bondage. Something happened on flight 815 to make them face their lives.. and that facing is the island adventures. Jacob's touch is each person's individual experience that sparked each one of them on a troubling, unenlightened path.
What we see in Sideways, is the resolution, or not, of their experiences learned.