IMHO you should be dropping ALL artificial sweeteners for pre-contest. I know of some who get bloated from 'em. I use stevia as a sweetener. Read the stuff on ALL artificial sweeteners here: http://www.holisticmed.com/aspartame/
If you want to drop me an e-mail with your mailing addy, I'll send you some. I just mix it with enough hot water to disolve it then keep it in a bottle in the fridge (shouldn't "need" it but I think this keeps it fresher). I use an eyedropper and about 4 drops is enough to sweeten a cup of coffee. Use too much and it can get on the tad side of bitter - so more is not better. It's suppose to be like 100 times sweeter than table sugar.