Our team is actually going with two custom built analog sensors, we like analog because its not just a 1 or a 0, it brings back a range as it slides on and off the line, so you can actually program for it to follow a line quite fast with only one sensor as opposed to having 3 - ... 9 sensors
Our sensors have a potentiometer on each that allows us to adjust the sensitivity and they each have their own LED light, so they could even follow a line if it were in a dark room. (not that following lines in the dark is useful for the competition, but its something its capable of)