Zero (or near zero) calories is good for people with diabetes. Full sugar is good for the rest of us. Only people who are fooled into thinking that artificial sweeteners will help them lose weight might go for the half/half version. But then, they are so fooled, that they'd go for the full zero calorie version.
diet versions aren't really all that good for diabetics either.
And they certainly won't help anyone lose weight. It's not because there is nothing wrong with sugar, quite the contrary, sugar is terrible for you if you consume it in everything you eat. We don't need nearly the amount of sugar we consume on a daily basis - some parts of the world have this figured out, naturally, through their cultural cuisines. Others, like us here the U.S., need to drastically cut back on sugar consumption.
It just so happens that most of the commonly-used artificial sweeteners are still worthless and terrible... they might not have calories, but they still trick the body into an insulin drama.
I think stevia and the sugar alcohols are the only sweeteners that do nothing to the insulin levels in serum.