My old vinyl skirts used to leak with any amount of rolling. I needed something that wouldn't leak after rolling, so I did a lot of research. I finally came up with the snap dragon ocean trek after talking to someone who really liked it.
I called the manufacturer to make sure I got the right size for my waist (35) and the cockpit combing (Tempest 170 rm). The rep who answered the phone was real helpful and his suggestions worked perfectly.
Since I've had it I have done a lot of rolling and never gotten an ounce of water inside the cockpit.