Why in the world do you want disc brakes for a crit? If you touch your brakes in a crit you loose 20 spots, so there’s no advantage. The weight will be a penalty accelerating out of turns, and responding to attacks. And a disc brake bike with thru axle will slow your time getting a wheel change, which depending on where you flat on the course and how long it takes to get back to the pit, could mean not having your wheel change completed as the pack comes around at the end of your free lap.