I can't see myself watching a beer brewing competition reality show per say, but I probably would watch a home brewer version of Beer Geeks. It could start on a trip to the LHBS with some instruction about the ingredients to be used in a batch of the home brewer's best recipe, then a brew session with a discussion of the home brewer's brew philosophy and a tasting of a previous batch, and end with a trip to the home brewer's favorite local watering hole.
You'd have to feature outgoing home brewers with lots of personality. I'd recommend Denny for the pilot.