Switching to Spark

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I have a daily Rockstar habit. This is apparently terrible for you but I need the extra engery after lunch and I think the mega-B vitamin dose I get helpful. I am considering swapping over to Spark but I am having a hard time finding information that doesn't end with someone trying to sell me something. Anyone here have any experience with Spark? I will note that I am not doing a 24 day challenge or cleanse and that my running club has a 40% discount so the price per serving is about $0.50 less than I am paying now for Rockstar.