I do think from an engineering perspective that your definition of composite is flawed. The bearings are certainly hybrid but that is not the same as composite, nor is the ceramic silicon nitride a composite. First a composite material are two different materials that are combined to provide a material property different than the two (or more) materials individually. Typicaly thought of as fiber and a resin in todays day and age (rags and glue). It does not need to be this way it can be concrete, a mixtrue of portland cement, gravel and sand, or a natural composite of wood. the ceramic balls and stell races do not interact this way, they are merely a mechanical system. The silicon nitride also on its own is not a composite material, it is silicon nitride that is formed into blanks by a sintering process of applying heat and extreme and pressure as the agent, no matrix or “glue”. Funny enough I have heard in technical papers carburized steel referred to as a “self assembling nano composite” (bearing steels are carburized). This is actually a more accurate definition of composite that silicon nitride as you have iron as the matrix material.
All that being said no one is going to be beating you due to ceramic bearings. Most karts I have encountered have atrociously dirty bearings, keeping your bearings clean will result in longer life and better performance where ceramics have the real improvement is in product life. I am sure many will argue this and I don’t really care.