Coming in on this late with my observations (from an old-timer).
NMM really is the fad of the day, whether it will last or not, we really can\'t tell yet.
Personally, I find that it is a lot of work for something that almost, but not exactly, looks unlike metal.
The vast majority I have seen here and other locations, the \'silver\' looks like stone and the \'gold\' looks like amber. In maybe 1% of examples does the effect really look like metal. I am also one of those that find the static, 2-D nature a problem.
That said, you can do some wonderful effects with NMM, it it is a very useful method of teaching how light falls and is reflected on surfaces.
If an individual painter thinks it will work best, I think they should use it. If you think you should use it because it\'s trendy or \"you have to use it to score well\", then you should reconsider.
I find it interesting that there has been little mention of the scale metal replication paints like Metalizer or Alclad. These were developed for the scale aircraft hobbiest and produce increadibly fine and realistic metal surfaces that you can tell steel from aluminum with. They produce a finish that I find very satisfying and produce a reflectivity that works extremely well on weapons and armor.
For contests, I do tend to avoid figure contests because so few use objective standards and primiarily use the \"judges stare at the models for a couple hours\" method, then they declare a winner. This judging is susceptible to biases in the judges, both to individual and to techniques. If a judge things NMM is the best thing since indoor plumbing, the judge could easily (and unconscioulsy) use presence/absence of NMM as a scoring point.