My educated guess...
As stated by Novak, the purpose of the Light motor is to provide a different feel by providing slower acceleration, softer drag brakes, but similar top speeds and will be very useful if you run in dusty/slick conditions.
I checked out the BL motor chart at the Novak website. The Light motors have a lower Kv rating than their equivalent wind Velociti versions. This means top RPM will be lesser on the Light motors than the regular Velociti motors.
If I were to get a Light motor (curious to try but I can't afford one yet). I'd probably get the 6.5L for my B4 (currently 7.5R 81/21) so that Kv ratings will be closer and probably gear it about the same or a tooth less depending on the feel of the vehicle on the track and motor temps.
If I do get a Light motor later on, I'd also wonder how a Light motor will feel with a 13mm sintered rotor.
I'm not too keen on the 13mm sintered rotor on the regular Velociti motors. The regular sintered rotor already have gobs of torque for off-road. Maybe in the long run as the rotor magnet weakens, the 13mm sintered rotor will feel similar to a new regular sintered rotor.
Just my thoughts on this matter...