CJ, according to their airbrush application guide on their website, they don't seem to recommend the fine needle 100's for use with enamels, but the medium 100's do get an enamel recommendation.
http://www.badger-airbrush.com/pdf/Catalog%202002%20page%202-3.pdf
I assume then that enamels have larger pigments that won't as easily slide past the fine needle and tip? If that is the reason for Badger's recommendations, the problem is with the paint and not the AB, so I wouldn't worry about it. When I was still using my Aztek, I did some experiments with the fine tip, which I believe that Aztek also recommended against with enamels, and found that it did work but was more prone to clogs.
Andy