Well, yes and no. Number one, there is real question about the existence of the G-Spot. Read my sticky on what we know.

Secondly, rubbing the fornix without passing over the so-called G-Spot is impossible. I do not know how one would distinguish one from the other.

As alluded to in response to your other question, there are no nerve endings in the vagina. So in either case, fornix or G-Spot, something behind the anterior wall of the vagina is really being stimulated. Various theories included pleasant irritation of the urethra, stimulation of Skene's glands and manipulation of a ligament that holds the bladder in position. None of these is proven or disproven and many (including me) think the pleasant effect is from some combination of these. There is also a major school of thought among sexologists and gynaecologists that whatever is doen eventually is dragging the hood of the clitoris up and down and all orgasms originate from clitoral stimulation.

I long ago checked out of that debate because there is no way to prove that one thing is "better" than another. As long as I end up on a highflying trip, I could care less what my partner is stimulating.

Somebody correct me if I'm wrong, but I thought that orgasm occurs due to stimulation of erectile tissue. In the male, the erectile tissue exists in the penis (obviously). In the female, the erectile tissue is in the clitoris, but I believe that it also extends into the body and divides on either side of the vagina. So perhaps when people talk about stimulating the G-spot, they are really talking about this internal extension of the clitoris.