Well, for one thing, anything that hasn't been tried has been tried for one of two reasons: It doesn't work, or they aren't comfortable that way. I would guess there have been plenty of ambidextrous people, but as I can't name any off the top of my head, I'll leave that out.
Assuming it doesn't work, there's probably a reason. And once you discover that reason, you can easily find ways around it. For instance, it is hard to switch between hands, you can easily defeat that argument by just hitting a 1 handed backhand when you're rushed. Anyone able to hit a good forehand should be able to hit at least a passing backhand, by my figuring.
If it is just uncomfortable, then all the easier to remedy, you can just as easily be the first if you'd like. All it takes is a lot of practice. Admittedly, for someone like me, it would also take some strength training in my wrists and forearms on my left hand, but even still, I've been trying to gain ambidexterity, and to some degree, I'm quite a bit like someone who just picked up a tennis racquet now with my left hand, a great improvement over the complete lack of ability to even attempt a left-handed shot.
Oh, considering! There was one person I know hit two forehands, and he was on my high school team last year, playing doubles. My coach was kinda wierded out about it, but since he was more comfortable with it, she allowed it. He did that to some degree of success, it wasn't in any way detrimental that I know of.
