Here’s a side by side photo of my Seamaster 300m Heritage (AR on the inside of the crystal only) and my Aqua Terra Skyfall (AR on both sides of the crystal). The photo was taken in my office under fluorescent lighting. You can easily see that the Seamaster’s vintage style bubble crystal, which has only the interior AR coating, shows significant reflections that make the dial harder to read than the dial on the AT which has a crystal with AR on both sides. That being said, I don’t find it difficult to tell the time on the Seamaster because it’s highly polished, rhodium plated and beveled hands reflect light like a mirror. So AR on both sides of the crystal is a double edged sword: it enhances dial readability, but the exterior coating is almost certain to pick up scratches as time goes on. You pays your money and you takes your chances