The top two CZN’s are from Global Flyfisher site and show a more streamlined nymph profile. The bottom fly was tied by Steen Ellemose of Denmark (2006 Siman Ltd. site). I have tied and fished both styles of the fly. My preference for a CZN trout fly is the more slender profile. I have had best luck with earth tones and if a hot spot is incorporated into the fly’s mid point or thorax design it is small and usually a bright green or orange. I have not experimented with other colors. Really, I have had to pay particular attention with the presentation and staying in direct control. My catch rate goes up significantly when I focus on the line control. I have the same results with a GRHE, an egg pattern or the CZN. But, I enjoy the looks of the CZN. The technique has, thus far, worked for Rainbows, Steelhead, Chinook Salmon, Chum Salmon (no, I did not snag them) and Whitefish.  Also, I have had best luck in 3′ deep or less water. In deeper water, I am distracted by wading and stability. Now, I don’t fish with more than two flies and often just the one. On a lake, I don’t go beyond two flies as that invites trouble, especially at last light. On a river or stream, I know I reduce my chances with  fishing only one or two flies. The last several years on moving waters, I have only fished or nymphed with the CZN’s. Many say flourocarbon tippets are not required but I am a firm believer in the 100% flouro material. I have not had problems with knots or abrasion.    

I would suggest from a short timers experiences that you keep the abdomen of the fly slender and save the gnarly bug look for the thorax area.