I like most of the color combos tried but still find something wanting. I think the comment about the grid hit home with me---it seems too mathematical, with lots of small boxes of near equal size within fewer bigger boxes also of equal size. Feels like the rigid repetition needs to be broken up with something that skews the regularity of the pattern a bit, making the red and grey bands different sizes or varying the two accent stripes in each bigger color band might make it more visually appealing. Just one man's O.