I recently went down a size to prevent bunching in the crotch area. I also have a small waist and huge legs. I wear PI Ultrasensors - XS. I love how the XS fits in the waist and crotch region, but I've been getting chafing on my thighs from the tight grip of the shorts on longer rides! I've been putting chamois butter on the area, which helps, but I still get redness from the grippers grabbing onto my skin! Anyway, it's much better than saddle sores. I say go with a smaller size AND shorts do lose their elasticity eventually, so you have to make sure and replace old stretched out shorts.