The OP was quite lengthy but what I came away with was "is trim primary or secondary?". By definition, and aircraft certification, trim is secondary. I learned to fly when airplanes were controlled by cables and later by hydraulics. I now fly FBW boeing and stick with my training. Trim should NEVER be a primary means of flight control. By definitions trim is a secondary flight control function. Maybe current flight training should focus more on actual flight skill rather than system management skills.