First off, I use Stevia, and try to avoid the ones with other additives.
Secondly, Stevia really doesn’t have anything to do with losing weight. You can eat snickers bars and lose weight. As long as you are eating at a deficit to your needs.
Third, the verdict is out on whether they are healthy or not. I would say better than some artificial sweeteners, but not as good as eliminating it entirely, and just sticking with fruit as your choice of sweets.
Finally, If you enjoy it, and it helps you cut lots of other crap out of your diet, I say go for it.

Of course this is just my opinion.