I made the kumquat wheat beer last year, and it won best of show in a local comp. out of 250 beers.
I used about 1 1/2 lbs. of halved Kumquats in the secondary for about a week and one half. There was a bit of re-fermentation, but I don't think there is much sugar in kumquats. When you slice the fruit in half, take out any seeds as they contain pectin which may adversely affect heading on the beer.
That recipe out of Zymurgy is excellent, though I also noticed the contradiction in the amounts of kumquats. A pound and one half seemed to be just right-- and I guess the judges thought so too. And I heard from a friend that was at the best of show round, and he said that they couldn't believe they were awarding it to a fruit beer.