I've locked up rim brakes on carbon rims on a flat course.
That said, if I were buying a new bike now, I'd go disc. The industry is going that direction, so you might as well go with it. I don't see road discs fading or going away any time soon. Yeah, there are a whole lot of compatibility issues with it, but if you end up doing cross or gravel, at least your wheels would be swappable with your road bike.