Weight – This is a no-brainer. While most hiking boots weigh 3-4 pounds, most trail runners weigh around a pound. Not only does this help your feet but keeps up the pace with less overall soreness.
Breathability– Trail runners are light, and usually built with mesh and Gore-Tex for water protection.
Flexibility – Along with a high torsional rigidity, most trail runners are built to get beat up. Along with a strong grippy sole and tough uppers, these shoes should easily contour to your feet’s needs and be easy to break in. Also keep in mind, despite not being touted as waterproof, if your trail runner gets wet it doesn’t take much to dry and won’t weigh you down if they do get soggy. Even better, there are a number of trail runners that are sold as waterproof.
Trail Runner Disadvantages
Little Ankle Or Foot Protection – In a trail runner you sacrifice the full foot and ankle protection you get from a boot. Most ankle and foot injuries on the trail happen in shoes. Unless sold as waterproof you’ll probably deal with water and rocks inside your shoe at some point as well.
Cheaper Materials – Many trail runners are made cheaply in foreign countries and can fall apart by just looking at them the wrong way. They can have all the features in the world, but if the seams can’t hold and the laces quickly whither away then they’re no good.