Hi, folks - just came across this discussion and hope to add some helpful information.
First, I've been in R&D for the last four years to create the first all-natural (no chemicals, preservatives, agave, maltitol or artificial sweeteners, including sucralose) sugar-free desserts in the country. The one rule that every dessert has to pass before being added to our line is that it be fine restaurant quality, and in look, taste and texture, be as good as or better than the 'real thing.' When we do taste testing with guests we do not tell them the item is sugar-free, and enjoy watching their jaws drop when we inform them after they give their detailed feedback.
We launch in a few months as Good For You Goodies. Desserts that are actually good for someone to eat. Why do I say good for you to eat? Because after the 60 Minutes expose on sugar (that would include ALL forms, including cane juice, raw, etc.) about how it, and not fat, is a cause of some types of heart disease and cancer, as well as the cause of obesity, insulin resistance and diabetes -- which the scientific community has known for years -- it should be clear to any thinking person that avoiding this toxin forever is imperative for long-term health. But back to sweeteners.
Why no agave? Because until high fructose corn syrup, which is 55% fructose and in sufficient quantities will not only give you NAFLD (non-alcoholic fatty liver disease, now a raging epidemic in this nation's children) -- agave syrup is 77% to 99% fructose! Sure, it doesn't raise blood sugars, but that's only because it's handled by the body differently than glucose, in that it goes straight to the liver for processing. If you want to get very, very sick, use lots of agave syrup. Maltitol is bad because unlike other sugar alcohols (xylitol and erythritol, which the body cannot 'see' and therefore excretes without effect on blood sugars), it will spike insulin and blood sugars: a double whammy. Upshot: Avoid. And Stevia? My medical and science research, as well as real-time work with Participants on my blog (see below), show that it interferes in metabolic processes involving fat accumulation (though I haven't yet pinned down the biological pathways) so that's out. Just as well, the stuff is bitter no matter what brand, or how it's used -- and I've tried every single brand and type on the market. Truvia is truly disgusting.
How do I know all this? I run a blog on the Science of Nutrition, Obesity and Diabetes: Sugarfreegoodies
But back to chocolate. After years of experimenting, it became clear that creating chocolate bars or candy for mass production without agave or maltitol was impossible. Either it tasted bad, gave you the runs, or both. And it cost a fortune, making retail prices prohibitive.
Instead, I concentrated on chocolate desserts, where unsweetened chocolate could be melted and, with the alchemy of natural sweeteners I spent years, blood, sweat and tears to discover, come through the looking glass as fabulous ganache, brownies, etc. The sole exception is my sugar-free chocolate chip cookie, for which we use Callebaut 86% chocolate drops, so they will be labeled "No Sugar Added" instead of "Sugar-Free." Our initial line will consist of those brownies and cookies, plus sugar-free vanilla ice-box cheesecake, chocolate truffle cheesecake, chocolate ganache-covered peanut butter mousse bars (all three of which have a puffed rice chocolate crunch crust testers cannot get enough of) and various flavored scones.
In other words, better to use already existing high quality chocolate for desserts instead of trying to re-invent the wheel on bars, IMHO, at least for now. There are a few natural sweeteners coming on the market in the next few years that might make me rethink this.