This article straight from the FDA may help clear up some things.
http://www.fda.gov/fdac/features/1999/699_sugar.html. Now, the FDA isn't the be all and end all but it is certainly more credible than what some guy claiming to be a doctor writes on the internet.
From the article:
Saccharin:
"In the late 1970s FDA and NCI conducted a population-based study of saccharin's role in causing bladder cancer in humans and found that "in general," people who used the sweetener had no greater risk of bladder cancer than the population at large. However, the study found "suggestive evidence" that heavy saccharin users--defined as those using six or more servings of the sweetener a day--may have an increased risk. Laumbach says that for consumers who use saccharin, the key to a lower risk may be moderation, as is the case with many foods that can cause problems when eaten in excess. Other health groups, including the American Medical Association, the American Cancer Society, and the American Dietetic Association, agree that saccharin use is acceptable."
Aspartame:
"While questions about saccharin may persist, the safety of another artificial sweetener, aspartame, is clear cut, say FDA officials. FDA calls aspartame, sold under trade names such as NutraSweet and Equal, one of the most thoroughly tested and studied food additives the agency has ever approved. The agency says the more than 100 toxicological and clinical studies it has reviewed confirm that aspartame is safe for the general population."
Sucralose:
"Also known by its trade name, Splenda, sucralose is 600 times sweeter than sugar. After reviewing more than 110 animal and human safety studies conducted over 20 years, FDA approved it in 1998 as a tabletop sweetener and for use in products such as baked goods, nonalcoholic beverages, chewing gum, frozen dairy desserts, fruit juices, and gelatins. Earlier this year, FDA amended its regulation to allow sucralose as a general-purpose sweetener for all foods."