Official Answer:
Mike Martus:
Page #8 of the 2011 OCCRA Rules, section - VGR13 states:
VEX sensors are the only ones that may be used and only two of each type of sensor that were given to each team in the kit of materials ( optical encoder, ultrasonic, light sensor, line tracker, bumper and limit switches). The line tracker VEX kit comes with 3 line tracker sensors; all other sensors are limited to 2.
So the official answer is NO. You may only use sensors as described in rule VGR13
According to the rules, the only allowed sensors are:
VEX Ultrasonic Rangefinder Kit (2 pk.)
VEX Optical Shaft Encoder Kit (2 pk.)
VEX bumper switch (in starter kit)
VEX Line Tracking (3-sensor) Kit