Burnout? Or nah

My 1 cent.
Could work quite well, although you will want to be careful that your pneumatic break has charge and that you actually activate it. Although because of the nature of the rules you are losing two motors so if you can design a fast motor break that uses one motor (or even two) it might be a better use of motors.

Team 62 did this pneumatic activated brake and it looked quite cool.

The surface area of the brake to the mat will probably dictate its effectiveness. So if you have a huge plate with the anti slip mat holding you in place that would have much more grip than a few holes of a c-channel.

Mass is probably area number two for dictating braking and “you shall not pass” effectiveness.