I've been commuting with a CB for a long time. Single speed during the summer, and this winter I finally got a Sturmey S3C working.
When I first moved to town, I lived at the top of a very tall hill, and my CB would fade by the time I got to the busy intersection at the bottom. You can't change the laws of physics. The energy gained from the descent has to go somewhere. This has been discussed at length with respect to other types of brakes. I basically had to ration my brake by descending more slowly, thus letting the heat dissipate over a longer period of time. Also, pulsing the brake probably lets the grease circulate a bit during a long descent.
This will either be a minor inconvenience, or too annoying to tolerate.
I also had a couple of close calls that convinced me I need a front hand brake. Then you can also distribute the braking load between front and back. I love the simplicity and aesthetics of just a CB, but for commuting, one has to consider utility and safety.