Sucralose, the actual sweetener in Splenda is the most studied and accepted low glycemic sweetener on the planet. Unfortunately for Splenda's powdered version the carrying agents are dextrose and maltodextrin which are both carbs which causes powdered Splenda to contain hidden sugar. We developed FTS ZERO and carry the sweetening agent Sucralose to you using purified water eliminating the carbs entirely. Any product you see sweetened with Sucralose, commonly labeled Splenda on many packaging will be sweetened with Sucralose by itself eliminating the dextrose and maltodextrin. Splenda chose the powdered format to compete with what the public was used too, packaged sugar.
The claims you see are erroneous, just like the claim that soda sweetened with Aspartame turns into formaldehyde if left in the heat. I hate urban legends formed on the web...but hey, it's like the wild west out there
All the answers to your questions can be found here-
http://www.splenda.com/faq/no-calorie-sweetener