I actually have this shoe and used a product called "Shape-up" on the grey part and the entire mid-sole. I first blacked it out with a sharpie marker and then put 2 light coats on the mid-sole. It hasn't cracked and has been on the shoe since the start of the season.
PCA products
I don't recommend that you put it on the leather part of the shoe itself as id does crack on the shoe over time.