I believe that Coach45 and RPM Pitching does the best work when it comes to teaching high-performance and non-injurious techniques. The NPA's program includes some bad things IMO such as non-specific drills such as the towel drill (pitchers do not release out front), Fast Arm / Double Spin Mechanics (Marshallites would know it as "Looping"; it creates a timing flaw), and once advocated the Flex-T position (this later led to the "hanging arms" mechanics inspired by Paul Nyman that you see in Anthony Reyes and Mark Prior).
However, their emphasis on specific conditioning and the gradual adoption of the pronated release of all pitches shows that they are learning something.
I don't claim to be a pitching expert like Chris O'Leary or Dr. Marshall, and I think it's dangerous to affix that label anyway, so take my advice for what it's worth - an amateur's.
Owner of Driveline Baseball - Seattle, WA