I used some Stevia in a few glasses of unsweetened skeeter pee.. Not bad for a diet drink.. A little bit goes a long way, I used 1 packet per 16 oz glass..
It was added after Pee was fermented dry and cleared on a per/glass basis, not in bulk. Haven't tried splenda, so I can't comment on the flavor.. Another good thing about Stevia is that it is not fermentable.