I accept that you believe that, but there are plenty of Less Wrongers who disagree. So this is a matter of difference of aesthetic preference about one's thought processes, rather than a matter of objective statement. After all, even "I notice I'm confused" or "update your beliefs" are slogans, and they seem to be conducive to good epistemology.
Both of those slogans can be used to justify bad epistemology, e.g. the first to justify rejecting a factual narrative that actually happened but doesn't happen to correspond to your pre-existing beliefs, and the second to assume that something is probable because a lot of people you know happen to be arguing for it.
Happy to share that, after multiple rounds of feedback, here is the set of rationality-themed T-shirts and bags with the slogan that got most support from the community, "The Difference Between Medicine and Poison is Dosage."
These t-shirts and bags are an effort to update based on the feedback received on the original set of rationality shirts and optimizing suggestions. This includes use of graphic images in the words, use of more professional designers, etc. We went back to the drawing board, and tried to design a new shirt that used a slogan that was quite popular. We ran the design by the Less Wrong FB group a couple of times (1, 2) and this is the final product.
As you can see, there are two styles available, one with "Dosage" empty and with the image of the dropper, and one with "Dosage" filled in and without the dropper. Various colors, sizes, and materials are available for each shirt/bag.
The first style is available for purchase on CafePress here.
The second style is available for purchase on CafePress here.
Look forward to hearing about your experience and thoughts about these t-shirts and bags, and the impact they make in carrying good rationality-themed memes into the world! We will be making more shirts and running them by the community as we did with these. All revenue will go into promoting rational thinking strategies to a broad audience.