NNL stands for Nameless National Luminaries. If I recall the story right there were about 6 championship caliber modelers that held the first NNL event. It seems these guys were disgruntled with the IPMS judging format, to fix that they made thier show a "people's choice". Having done both NNL style & IPMS judged shows, I can say that both have ups & downs.
A small local NNL can end up as a "members only" affair. I've been kicked out of a class where my model was oviously dominant, because the club Prez. usually dominated that class. (Box Stock with an Accurate Miniatures Corvette) The shows put on by this club were ALWAYS a fun time, despite the relatively minor aggravation.
The majority of shows I ve attended are IPMS judged events. In these shows I keep getting docked points for out of scale plumbing & wiring. The two local chapters' shows are predominantly military modelers & thus they don't notice minor changes in a car model. IE I pointed out the Vette suspension on my '69 Camaro & the judge was like "that's not stock?". Again I ALWAYS have fun at a show, despite small things like these.
If your club concentrates on it's show, then I'm afraid the members may lose sight of thier purpose..... the models.