Depending on the shape of your head, the 777 is either one of the best- or worst-fitting helmets available. If it takes to your noggin, it’s snug but not tight and secure without pinching. But if the 777 and your bonce don’t immediately bond, then forget it.
However much you adjust the chin straps or retention band, it just feels like it’s about to catapult itself off your cranium. Only coming in two overlapping sizes (M: 50-57cm and L: 55-61cm) might be what makes it so divisive. If your head is 55-57cm then you might find that neither size is quite right.
Whatever the size of your head, the 24 vents will at least keep it cool (and the front seven also get net screens to keep bugs out). Approach it like you’re on a night of speed dating. Give it two minutes of your time and, if you don’t hit it off, move on to something else.