I would venture to guess that the issues related to crystal light have nothing to do with the sweetener and instead to do with how incredibly acidic it is. If you drink that all day every day.. I could see that causing problems. Didn't give me stomach issues but sure as hell caused some major gum problems. IMO... sucralose is a great sweetner without gastro sides.
Was thinking acidity as well.
But I was reading some surprising things on artificial sweeteners.
I'm trying to drink an extra two quarts of water a day. This is a struggle without sweetener..