I love Saucony's and have worn them for years. Mostly I walk, not run, and they offer the best support. My right-foot size, for casual and dress shoes, is a solid 8.5M; my left foot is slightly smaller. I always purchase my running shoes 1 to 1.5 sizes larger.

In this case I ordered a 9.5M and it was too short and too tight across the top of my foot (as opposed to my other review of the Grid Cohesion 5 Running Shoe which is just right at 9.5M). My toe was at the end of the shoe. Even while sitting,my toe was uncomfortably pressed against the top and end of the shoe.

I reordered the shoe, in a 10, and it fits very nicely. Differences between this and the Grid Cohesion 5...this one: has more padding in the ball of the foot (between the ball and the pads of the toes depending on the fit); the back of the heel is higher and may rub a little if your ankle is not used to that; wider fit -- the shoe, overall, is wider and shorter. Take that into consideration when you place your order.