Aspartame - searching for the truth

There's this article.

It sets out to make the case that arguments against aspartame as a sweetener are garbage science. That's fine, I can handle that - you'd then expect that a good scientific argument would be presented to show that aspartame was safe.

Strangely, that's not the way the article goes. It refers to an "Iowa group" (though there is no actual traceable reference - bad science) and then says:

Of women who drank two or more diet drinks per day, 8.5 percent had some sort of heart disease. But, for women who either drank fewer or no diet drinks that number was only 7 percent.

And then it argues:

What is really going on here is a classic case of mixing up cause and effect. No, diet soda doesn’t give you heart disease. You already have more heart disease and drink diet soda to try to cut calorie consumption.

Let's assume that the sample of 60,000 people is divided into two, each numbering 30,000. 8.5% of the "user" group numbers 2550; 7% of the "non-user" group numbers 2100. So the article smoothly concludes - there are more people with heart disease in the "user" group, therefore there is no evidence that sweeteners are causing heart disease.

But the author hasn't made this case. It may be that the case is there, that the paper being discussed doesn't support the conclusion. But by short-cutting to the author's own conclusions and missing out the important science-y bit, the author is just as guilty of bad science. We don't know what expected levels of heart disease are (whether the "user" group is unexpectedly high, and the "non-user" group is unexpectedly low) ... or whether the reason the rate of heart disease in the "user" group was higher because of previous consumption (in other words, it had already caused the heart disease, the "smoking gun"), rather than trying to mitigate the effects of heart disease ... or whether the "user" group and "non-user" group were otherwise identical .... The web article, having failed to properly reference an article, then simply disagrees with the interpretation of the results, and accompanies this disagreement with name-calling and various other approaches designed to close down the debate, which pretty much amount to "only dumbasses would believe this".

I am pretty good at science, and I don't know the truth about aspartame. I am genuinely interested to know if, in addition to making drinks taste disgusting, there are health issues that I ought to be concerned about, especially because it's becoming less and less possible to find naturally sweetened alternatives in supermarkets. So I'd appreciate it if both sides could cut out the arguments that don't stand up to critical analysis, and do a proper job.

One more thing. Levels of childhood obesity were significantly lower in the 70s and 80s, and at the time, drinks containing artificial sweeteners were far less common. There's a causation/correlation thing here, of course - lower levels of obesity were doubtless due to more active lifestyles and so on rather than the sugar we consumed. However, what would be most interesting would be evidence that demonstrated that use of artificial sweeteners actually improved health - preferably produced by an organisation that wasn't financially benefiting from their sale. If that evidence isn't there, then why can't we just stick with natural products? I'd rather consume what has been produced by a farmer than what has been synthesised in a laboratory, given the choice.