For hot weather racing, and especially in the humidity (think Florida), I would opt for this upper over any other carbon fiber plate racing shoe on the marketplace. Saucony really strove for high breathability in this third iteration, and they did not sacrifice a secure, lockdown feel in the process. With a semi-gusset toward the top of the tongue, the running shoe designers really nailed the reaction happening between the laces, eyelet chain, tongue, and heel counter. A very small detail that many marathon runners would not notice is the material choice for the heel counter and heel pocket. It is not smooth, and for good reason. The last experience a road marathon racer wants is heel slipping. The friction created between the sock and the heel counter is key, to ensure zero slipping through the toeoff. Any lost energy through each step is detrimental to overall performance of a marathon racer. Although I did have some heel hot spots in the testing, I’m not hearing many reports from other runners of this issue.