I have had taken ATCN and TNCC. Both classes are informative and usefull. What I liked about ATCN over TNCC for my work situation is, we are in the same class with the same doctors I will be working with. We get the same lectures. When I respond to a trauma activation, I know what they have been taught, and how they should be running the activation. If things go wrong, it is so much more effective to say "ATLS guidelines are...." I was recertified this year for ATCN and it was a difficult test!