At the end of the day hheltzer, you need your brakes to be far more efficient than your motive power..
If you can't reliably stop in "ALL" condition, you've got serious problems if reqiuiring to make a panic stop to avoid injury.
In dry conditions, rim brakes are acceptable, but suffer from poor braking once the rim heats up and the area where the two sections of rim join together start to distort; causing ever increasing brake pulsation - not a good thing.
In wet weather, rim brakes are less than useless.
Disk brakes are by far the best method of stopping as they work well, regardless of superficial rim damage or if the conditions are soaking wet.
Disk brakes (and the most powerful mechanical combination you can get) are the way to go, as they allow a dual pull arrangement, unlike hydraulic setups.
Fabian