TX, even most of the German sausages that you will find here won't have the level of flavor you need to put in gumbo.
I've made gumbo with the chorizo and it has a good enough flavor to contribute, better I think than almost any sausage you'll find imported. The salchichas (sometimes the come in a "wheel") are basically the same thing only smaller versions and come in tubes. They might be better to use than chorizos because they'll hold together better.
I chill the chorizos (close to freezing would be good, but no ice crystals), cut them in half long-ways with the sharpest knife I can manage (and sharpen it every few cuts). then slice them about a quarter-inch thick so you have half-moons. I then brown them pretty good and quick so that they hold together when they cook. But I put them in only about an hour/45 minutes or so before the gumbo's done so they don't get too mushy. I put some of the grease from cooking them in the stock so the flavor gets mixed in - cook the sausages two hours before the end, put the grease in, chill the browned chorizo chunks, then put them in an hour before end.
My biggest problem is finding okra. I have found some in China Town a couple of times, once at a verduleria and once in a small supermarket there.