the long term effects of it are unknown. 'experts' suggest sticking to things that have been tested more thoroughly, although they may not be so good for you, either.
splenda makes me sick. it brings my entire intestinal system to a screeching halt.
more here:
http://generationgreen.org/2005-01_lead-story.htmstevia is from a plant, and if you drink herb teas, you can just add the plant to the brew. i have never used the processed stevia, so i can't say.
i'd prefer to use a little real sugar, and just cut back on the sweets!