I haven't found any 'diet' drinks sweetened with the natural sweeteners yet, even at Whole Foods! Their diet drinks contain sucralose or Splenda- talk about selling out!
Once in a while I do have a diet cola (like maybe once a week). My roommate keeps the pink Crystal Light around and whenever I have a glass I'm ravenous and dizzy like 20 minutes later- it's the chemical sweeteners. And, artificial sweeteners do cause a raise in insulin (but not blood sugar), which also promotes fat storage and hunger.
I love my Diet Pepsi, and when I have it once a week I remember to tell myself that I'll be hungrier than normal after I have it. As long as I know what's going to happen I can prepare and not eat too much. But seriously, how hard is it to just put agave nectar or stevia in a drink instead of a chemical? The big corporations need to use their head. But I guess the chemical ones are cheaper. :P
Actually this summer I'm going to make homemade iced tea and keep a pitcher in the fridge, and put some stevia in it. That should curb my craving for those cold, flavored summer drinks.