He he he, this should be good.
Off road there is no question that discs shed mud and water better than drumbs. Wet and muddy brakes don't stop.
That said, if clean and dry I've seen some drumb brake sysems that flat out rocked in stopping power. Drumb brakes by their design have more pad surface area and cool equal or better to disks. I've spent way more time bitching about disk brakes than drumb systems in general.
Drumbs can shed water pretty fast but not as fast as disks. Once drumbs load up with muddy glorp its all over and disks win hands down.