I've experimented with reducing and giving them up completely, and for me, I don't see any difference. Personally, I believe that it may be possible that if you're not counting calories, you might unconsciously eat more when you're using artificial sweeteners, but it's ultimately calories that determine weight loss.
That being said, if reducing or eliminating sweeteners, reduces your hunger and cravings - that's reason enough to try it. Reducing carbohydrates does that for me dramatically, and artificial sweeteners help me reduce my carbohydrates, so I chose moderation over elimination.
I can't stress enough though, that experimentation is a very useful tool in finding what does and doesn't work for you.