I just read the complete Arc chat transcript (very interesting) and Peter mentioned something that should calm some people down over the brightness of the Arc4x compared to the Arc4+. Someone asked Peter how much brighter he expected the Arc5 to be compared to the Arc4. Peter replied that he was hoping for a 30-40% increase in lumens. Then he said the difference was barely visible, but was a step forward. Correct me if I'm wrong, but the Arc4x is said to be 40% brighter than the Arc4+. This means that the Arc4x increased brightness will be virtually undetectable unless you compare both lights side by side. I think those (including me) who own the Arc4+ and those who have ordered one should be extremely happy with the light and not feel that they have an "inferior" product that doesn't measure up to the Arc4x. I am more satisfied with my Arc4+ everytime I use it. Just thought I'd let you know.