The key is in "on the roads, not the track." Since you're not on the track trying to set a track record, and there are dangerous obstacles on the roads, why not just ride down with maintenance throttle with feathering of the brakes as necessary? If you're not approaching the traction limits of the tires, you don't need to worry if the weight distribution is 40-60 or 60-40. Going downhill requires extra braking distance due to gravity working against you. It behooves one to be cautious by going slower. Should an animal, loose rocks, stalled car, or tractor trailer obstructing your lane appear around the next blind corner, you may need the stopping distance.