Separating the "Certi" from "Rx" looks good, but separation might be a bit too much. Really have no preference for red vs.blue right now. Prefer not to see the tail of R and x form another x below; looks a bit menacing. Only discarded #1 because it looked just like #2.
re: #16, What do you think about having "Certi" on one side of the gray side of the tablet and "Rx" on the red? We don't necessarily want to see the tablet looking "broken" This might look good gray and blue or suggest some other color combinations.
re: #18, Could you get the background in a shape (oval, ellipse, shield, other) in tighter to the text? would be interesting to see without the abstract wymbol